The Solomon Islands and Their Natives

CHAPTER XVII.
THE CLIMATE OF THE SOLOMON ISLANDS.

Amongst the matters to which I devoted some attention in this group of islands, was the annual rainfall. As far as I know, there have been no continuous observations previously made there; and the only record of rain-measurement, which I have been able to find referring to this region, was an observation made on board the Austrian frigate “Novara” in the middle of October, 1858, whilst to the northward of St. Christoval, when three inches of rain were registered in five hours.[491] I therefore set myself to work to do what I could in this matter, making rain-gauge stations at Santa Anna and Ugi and keeping a register myself on board. Mr. Fred Howard undertook to make these observations at Ugi, and I supplied him with a rain-gauge for this purpose. His register, which extended over a period of fifteen months from October, 1882, to the end of the following year, was kept with great regularity; and as I was able to compare his observations with my own on board for a few days, I have every confidence in the accuracy of his observations. At Santa Anna, Mr. William Henghan, to whom I had supplied a gauge, undertook at first to keep the record, beginning in the last week of October, 1882; but he left the island two months after, when Mr. Charles Sproul voluntarily undertook to measure the rainfall, which he did with great regularity until the end of the following year. I regret to learn that Mr. Sproul has recently died at Sydney. He was one of those men who in a quiet inoffensive way have done much towards preparing the way for future settlers in this group. I have the greatest confidence in his observations, since for a few days at Santa Anna we were able to compare our daily measurements.

Before proceeding to consider the results of these rain-measurements, I will endeavour to convey to the mental eye of my readers a general idea of the most striking atmospheric phenomenon in connection with the rainfall of these regions. I refer to the oncoming of the black squall.

A clear and serene sky at first gives no token of the sudden change that is to quickly follow; but the stillness of the air and its increased dryness, together with the consequent greater scorching power of the sun’s rays and the apparent nearness of surrounding shores, give sufficient warning of the onset of the rain squall to those acquainted with these seas. In a short time a low black arch appears above the horizon, often in an unexpected quarter, and rising rapidly it sweeps majestically with great swiftness until it appears to span the heavens. Onward it rushes, quicker far than one imagines; and now must the navigator beware. Under yonder advancing arch a white line of foam marks its van. There, away towards one of its corners, a waterspout rises in fantastic shape; sea and cloud meet in mid-air and become intermingled in the whirling column. Lightning plays about beneath the arch and within its black mass, illuming for the moment its dark recesses and leaving it in the next far blacker than before. Peals of thunder herald on the advance of the black squall.

“Clear lower deck!” “Hands aloft!” “Shorten sail!” Such were the words of command which were almost daily issued during our cruises in these islands. In a few brief minutes, the ship is prepared to meet the squall. The temperature falls very perceptibly, and the officer of the watch gives a slight shiver as he dons his oilskins. The wind is freshening, a few large drops of rain fall, the men crouch under the bulwarks, and now the arch is overhead and we are in the thick of the squall. Down comes a deluge of rain which in less than a minute wets all who are unprotected through and through. The ship heels well over, even with her scanty canvas. There is nothing more to be done. We listen to the whistling of the wind in the rigging and patiently wait until the weather clears. In half-an-hour the arch has swept over us, and is pursuing its rapid course towards the neighbouring mountain-peaks, perhaps of Bougainville or it may be of Guadalcanar. The blue sky begins to show itself; and in less than an hour all is as before. With reefs shaken out and more sail made, the ship proceeds, plunging cheerily on under a fresh breeze as though glad to shake herself clear of the squall. The sea losing its murky colour reflects the bright hue of the sky now serene; and its white-topped waves sparkle in the sun. The wizard of the storm has shaken his wand, and the scene is changed, as though by magic.

All nature seems invigorated by this short battle of the elements and to be indebted to the bounty of the black squall. Whilst everything before was depressed and lowering, all is now bright and cheerful. Nature has in truth had its accustomed shower-bath, and the reaction that ensues does good to all; makes men the happier and the stronger, elicits a loud chorus from the lower creation in which bird, reptile, and insect, before hushed in the depressing gloom, now combine in strange medley; and the inanimate world shares in the bright change which has followed the storm.

If it be night, the increased luminosity of the sea may be the warning of the arched squall. The ship throws off a bright wave of phosphorescence on either side of the bow, and leaves a luminous track in her wake. Overhead the cloudless star-lit sky conveys its warning; for the stars shine with increased brilliancy, those of less magnitude usually invisible with the naked eye are now distinctly seen; and if the navigator, who has often tried in vain to count the six stars in the Pleiades, can do so now, let him look out for the black squall. Such are the warnings. Then sweeps along the lowering arched mass with its rain and its waterspouts, its wind and its thunder and lightning. On it comes, looking all the blacker as it spreads athwart the heavens and turns the star-lit night into a lightless gloom. Overtaken in the night by such a squall, unable to see more than half a cable’s length on either side, and perhaps in the vicinity of sunken reefs the position of which is uncertain, a sailor has need of all his wits. On one occasion, when in this situation, we came unexpectedly in soundings, whilst, as we thought, a hundred good fathoms and more lay beneath our keel. The time was anxious, but nothing could be done until the squall was over. When the arch has passed, the stars begin to show themselves, and in a short time they shine out with all their lustre.

With this description of the rain-squall, or black-squall, or arched-squall, as it may be also conveniently termed, I return to the consideration of the rainfall of this region; and first with regard to the observations at the east end of the Solomon Group. During 1883, 125·03 inches of rain were measured at Santa Anna, a small island lying at the extreme eastern limit of these islands. Two-thirds of the total amount fell in the live months between the beginning of April and the end of August. At Ugi, which lies nearly 60 miles north-east of Santa Anna, 146·24 inches of rain were registered during the same year. About one-third of the total rain for the year fell in the two months of April and July. On comparing the totals for each month at these two localities, there will be found to be but little agreement, which is due to the circumstance that the daily rainfalls of these two places have little relation one with the other, a heavy fall at one island being often only indicated by a slight fall of rain at the other. It is thus evident that locality has a great influence on the rainfall in this part of the group; and probably Ugi owes its greater rainfall to the proximity of the high land of St. Christoval. Here, as in other parts of this group, I often had opportunities of observing how the contiguity of land affected the rainfall in a single shower. I might have been in the interior of an island exposed to a deluge of rain for a couple of hours, and have found, as I did once in the Shortland Islands, that there had been very little rain on board. Another time, when in my Rob Roy canoe on the south side of Treasury harbour and not more than a mile from the ship, a rain-squall passed over me leaving scarcely a drop behind; but as it swept over the ship and was approaching the steep slopes of the island, a smart shower of ²⁰⁄₁₀₀ of an inch fell on the deck.

I cannot gather from the observations made in this eastern part of the group, that one season of the year has a heavier rainfall than another. On comparing the two records for 1883 of Ugi and Santa Anna, it might be thought that the closing months of the year would usually prove to be the driest; but on referring to the register kept on board the ship in this locality in the latter part of 1882 (page 365), which is one of the heaviest records we had in the Solomon Group, such an inference would be negatived. Nor do I find from these registers of rainfall that there appears to be any relation between the amount of rain and the prevalence or non-prevalence of the south-easterly trade, which usually becomes well established in May and lasts till the end of November or the beginning of December, when the north-westerly and westerly winds set in. These observations point towards the inference, therefore, that the distribution of rain through the seasons in this part of the group is capricious; and they do not warrant the conclusion that one season is wetter than another.

Perhaps a comparison of the number of rainy days, or days on which not less than ²⁄₁₀₀ of an inch of rain were measured, may help us to form a more definite conclusion. It will be seen that at Santa Anna and Ugi there were much the same number of rainy days, 182 in the former island and 178 in the latter, or in round numbers about half the total number of days in the year were rainy.[492] At Santa Anna, during the prevalence of the trade wind, there were on the average 15 rainy days per month, and at Ugi 13 per month; whilst during the months from December to April inclusive, when westerly and variable winds prevailed, there were 18 rainy days per month at Santa Anna, and 19 per month at Ugi; so that we may infer that in this year of 1883 there were fewer rainy days per month during the prevalence of the south-east trade, i.e., from May to November, than during the period of westerly and variable winds, i.e., from December to April.

I come now to the subject of the greatest daily fall of rain in this eastern end of the group. On the 13th of June, 1883, 7·73 inches were registered at Santa Anna; whilst at Ugi on the same day only an inch and a half of rain fell, a circumstance showing how confined in their areas some heavy rainfalls may be. At Ugi the heaviest daily fall of 5·75 inches was recorded on the 28th of January of this same year; whilst at Santa Anna only a little more than two inches fell on this day; and here is another proof of the restricted locality of heavy rainfalls. On the 20th of November, 1882, when H.M.S. “Lark” was off the east end of St. Christoval, 5·74 inches of rain fell on the ship; whilst only a small amount of rain was measured at Santa Anna and Ugi. . . . . . With reference to the character of the rain in this part of the Solomon Group, I may remark that as in other tropical regions it is very heavy. A fall of an inch in an hour is very frequent during a rain-squall; but not uncommonly the rain falls far more heavily. Thus, on one occasion on board H.M.S. “Lark,” when in this part of the group, 2·90 inches fell in an hour; and at another time 1·03 inches fell in 25 minutes, and on another occasion an inch fell in half-an-hour.

But inasmuch as heavy falls of rain are not peculiar to the tropics, since far greater falls than those above named have occurred in temperate Europe, we can only judge of the character of the rainfall in this region by the total annual fall and by the frequency of heavy falls. Thus we find that at Ugi, in 1883, on 56 days the fall exceeded an inch; and that at Santa Anna, more than an inch of rain fell on 41 days. At Ugi, the daily records on eighteen occasions exceeded two inches; at Santa there was a lesser number of falls of over two inches, viz. 11.

If I were to estimate the probable annual rainfall at the coast in this part of the Solomon Group, I should place it at not far under 150 inches. Although only possessing the rain-register for a small portion of 1882, I am of the opinion, from having spent a large part of the year in this eastern end of the group, that the fall for 1882 was heavier than the rainfall actually registered for 1883;[493] although this is but a conjecture, it enables me to estimate the probable annual fall with some confidence at about 150 inches at the coast in this eastern end of the group.

The observations made on board the ship amongst the islands of Bougainville Straits (Treasury, Shortlands, Faro, etc.) during portions of the year 1883 and 1884 now claim our notice. As shown on page 365, 60·43 inches of rain fell in the five months from June to October of 1883, this amount being a little under that which fell at Ugi (65·70 inches) and at Santa Anna (67·72 inches) in the same period, the two regions lying towards the opposite ends of the group. During the same period of the following year, we measured 67·66 inches of rain in Bougainville Straits, an amount a little in excess of that of the previous year. During the same periods, i.e., from June to October inclusive, in 1883 and 1884, there were the following number of rainy days, 120 in the one year and 118 in the other. At Santa Anna and Ugi, at the opposite end of the group, the total of rainy days for the same period in 1883, numbered only two-thirds of the amount in Bougainville Straits. During these five months in 1883 there were 16 daily records of over an inch of rain in Bougainville Straits; at Santa Anna and Ugi, in the same period, there were 23 and 26 daily records exceeding an inch. In the same period of 1884, in Bougainville Straits, there were 22 such daily records, but the total fall was about 7 inches greater than in the previous year.

I may now draw some inferences from the above observations. In the first place, it is probable that the annual coast rainfall of Bougainville Straits and that of the eastern end of the Solomon Group are much about the same, viz., about 150 inches: the chief difference between the two regions being, that in the former region, there are a greater number of rainy days and fewer heavy falls. The heavy falls, when they do occur, are not easily forgotten; thus, at Treasury we measured, in July, 1884, 11 inches of rain in 10 successive hours; but the daily record was only 8·09 inches, since the rain began in the evening of one day and lasted well into the following morning.

During the heavy rainfalls in these regions the streams swell in an astonishingly quick manner. Rivulets become turbid streams, the whole hill-slope discharges a continuous sheet of water, and the water rushes down the permanent stream-courses with the roar of a mountain-torrent. Large blocks of stone are swept some distance along the lower courses of the streams; and the trunks of trees are carried by each successive flood further and further towards the mouth of the stream.

It should be now remarked that the average rainfall for the year, which I have estimated from observations made in different parts of the Solomon Group at about 150 inches, only applies to the coast. It is probable that this estimate is generally applicable to the coasts of these islands, except on the lee sides of the loftier islands.[494]

This brings me to the question of the rainfall in the higher regions. The rainfall will increase with elevation until a certain height is reached, where the clouds attain their maximum density; at such a level the greatest rainfall will occur. I learn from an interesting paper by Mr. Bateman on this subject,[495] that it may be inferred that in the Lake District of England the greatest rainfall occurs at an elevation of 2,000 feet, which is the level of maximum cloud density. In India, an elevation of 4,500 feet represents the level at which the greatest rainfall occurs. In the Solomon Islands, a greater height will have to be attained before the level of maximum cloud density or that of the greatest rainfall will be attained. Probably I shall not greatly err if I assume it to be between 5,000 and 6,000 feet. I have already observed that the south-east trade, subject to its usual variations, is the prevailing wind in the eastern part of the group for nearly two-thirds of the year. Coming laden with its watery burden, it first strikes the eastern slopes of St. Christoval; but although the higher regions of this island must cause the rain-clouds to precipitate a large amount of their moisture, the higher peaks do not rise in sufficient mass to a height that would receive the greatest rainfall, the extreme height being 4,100 feet. The rain-clouds, with the bulk of their moisture, would therefore be driven over the higher regions of this island, and would deposit the greater part of their burden on the higher slopes of the mountainous eastern portion of Guadalcanar. Since this island, in its eastern portion, rises in mass to a height of some 5,000 feet and attains a maximum elevation of 8,000 feet, it does not seem probable that, during the prevalence of the trade for nearly two-thirds of the year, a considerable quantity of rain would be deposited on the western side of the island; and, that such is the case, is shown in the fact that the dense forest-growth that clothes the steep eastern and southern slopes of the island gives place, on the lee or west side of the mountains, to a vegetation which gives to the western portion of Guadalcanar, when viewed from seaward, the appearance of a savannah or a prairie.

The lofty mountain-masses of the east end of Guadalcanar, which forms one of the finest specimens of coast-scenery in the world, are usually enveloped in rain-clouds at their summits. But occasionally one of the peaks is visible above the thick cloud-covering, marking by its elevation, as it were, the line of greatest rainfall lying below. In the same manner the high peaks at the east end of Bougainville, which have an elevation of between 7,000 and 8,000 feet, may be seen occasionally to project above the rain-clouds; but there is, probably, a smaller quantity of rain deposited on the higher slopes of this island than on those of Guadalcanar, because the mountains are more isolated, possess for the most part the tapering volcanic profile, and do not rise “en masse,” as in the case of the high lands of Guadalcanar. The greatest rainfall in the Solomon Group takes place on the steep southern and eastern slopes of this island of Guadalcanar. Huge mountain-masses appear to rise directly from the sea to a height of some 5,000 feet, ultimately attaining a height of 8,000 feet. The fall there must be tremendous, especially when, as is frequently the case, the land of St. Christoval does not interpose itself in the path of the moisture-laden trade-wind. Then, loaded with vapours after its passage across a wide expanse of ocean, and with but a thin tract of intervening lowland to rob it of its moisture, the trade strikes at once upon the precipitous mountain-slopes as against some Cyclopean rampart. There is no ravine or breach in the mountain-mass to ease the tension. There, on those mountain-slopes, a terrific precipitation must occur, which, if the annual rainfall of the coast is 150 inches, will here be three or four times that amount. This is no exaggerated language, but is the opinion I have formed, after having carefully considered the physical geography of these regions.

The subjoined rainfalls of a few localities in other parts of the world may be interesting to compare with that of the Solomon Group:[496]

	England	32	inches.
	Singapore	97	„
	Atlantic Doldrums	225	„
	Western Ghats	302	„
	Cherraponjee	10	„
Solomon Islands.
	(a.) at the coast	150	„
	(b.) on the higher slopes of Guadalcanar	400	to 500 inches probably.

Comparing the rainfall of the Solomon Islands with some results obtained in other parts of the Pacific, I would draw attention to the small rainfall of Port Moresby on the south-east coast of New Guinea, where 34·44 inches were registered at the Mission Station in 1875.[497] In Fiji the rainfall appears to vary between 60 and 250 inches per annum, according to the degree of elevation above the sea, and to the position of the station on the lee or weather sides of the islands, the greatest annual falls occurring in the interior of the large islands.[498] In Oahu, one of the Sandwich Islands, during 1873, the rainfall at the coast was 37·85 inches; whilst at a distance of 2³⁄₄ miles in the interior, it was 134·06 inches, the elevation being only 550 feet above the sea.[499]

I will now make a few remarks on the barometric pressure, temperature, and other features of the meteorology of this group. They are based on the results of the observations made by Lieutenant Leeper on board the ship, and by Mr. F. Howard at Ugi. (Tables appended.)

As is usual in these regions of the Pacific, the fluctuation of the barometer, whether daily, yearly, or monthly, is very small. Thus, the range during the 22 months we passed in the group, was from 29·83 to 30·18 inches, or about a third of an inch; whilst the average monthly range was rather under a quarter of an inch, and the usual diurnal variation about ·04 of an inch.

Whilst endeavouring to compare the temperatures of the different seasons, I have mainly used the Ugi register, since it gives a continuous record for more than a year. At Ugi in 1883, the portion of the year from June to September inclusive was slightly the coolest, but the difference in the means was not 2°; and, in truth, taking all the thermometric observations into consideration, the seasons are scarcely distinguished by their temperatures. As Lieutenant Leeper[500] remarks in his report, the temperature varies but little all the year round, the monthly mean varying between 80° and 85°. The annual mean temperature may be placed at 82° to 83°, and the range from 75° to 95°. The daily variation is considerably affected by the exposed or protected position of any locality at the coast. Judging, however, from the data at my disposal, it is usually less than 10°, e.g., 79° at night, and 88° at mid-day.

From the hygrometrical observations, it may be inferred that the climate of these islands is generally very moist. The relative humidity, taking 100 as saturation, ranged at Ugi in 1883 from 54 to 100; but the monthly range was usually from 72 to 95, the mean for the year being 83.[501] This mean degree of relative humidity is much greater than that of Levuka in Fiji which would seem to average about 70;[502] but in truth there is little necessity for me to remark further on this well-known feature of the climate of these islands. Yet, I should add that this proportion of aqueous vapour would not necessarily be oppressive in a temperate latitude. In a tropical climate, however, any influence that retards the evaporation from the skin of the normally excessive perspiration, is a cause of personal discomfort, such as would not be experienced in a drier locality lying in the same latitude. The effects of this combination of heat and moisture are to be seen in the rankness of the vegetation, and in the rapid rusting of steel. Although the foregoing remarks may be taken as generally applicable to the group, it should be stated that on the lee side of a mountainous island, such as the western end of Guadalcanar, there is a comparatively dry atmosphere, and the difference is also shown in the character of the vegetation.

The moderate intensity of the sun’s rays in these islands is to be ascribed to the presence of aqueous vapour in quantity in the atmosphere. When, however, a thunderstorm and its accompanying rain-squall are portending, the air is unusually dry, and the sun’s rays are very fierce. At such times it often happens that the sky is overcast; and thus it comes about that the unwary traveller, by rashly baring his legs and arms, suffers severe sun-burns when he least expects it. Waterton and other travellers have, through ignorance of this fact, been laid up for several days, and even weeks. I was unable to walk any distance for about ten days, after experiencing a severe sun-burn of the legs as the result of baring them during an overcast day. The affection is peculiarly painful, though it often excites but little sympathy.

My remarks on the meteorology of this group will not be complete without a short reference to the prevailing winds. The South-east Trade Wind and the North-west Monsoon carry on a continual struggle for the mastery in these islands. However, for two-thirds of the year the Trade prevails, viz., from April to November. The appended record of winds, which extends over a considerable period, I have prepared from the observations made on board H.M.S. “Lark” in different parts of the group, and from the registers kept by Mr. Sproul and Mr. Howard at Santa Anna and Ugi. It will be there seen that at the eastern extremity of these islands, viz., in the vicinity of St. Christoval, the Trade announces its onset in April by unsettled weather, and frequent thunderstorms. In May, it becomes established, but, as Lieutenant Leeper remarks, it blows in fits and starts, is interrupted by calms, variable winds, and heavy rain-squalls, and does not blow home as in Fiji and the groups to the eastward. At the opposite end of the group, in Bougainville Straits, the Trade appears a month later, and does not become established until June. In this locality, however, it is more fitful than in the eastern islands, blows lighter, and is less to be depended on by the navigator.

It may be generally stated that the north-west and west winds set in about the end of November or the beginning of December, and prevail until the end of March. Although heavy gales accompany the frequent shiftings of the wind, especially when it is from the S.W., these islands are beyond the sweep of the hurricanes which in this season of the year occasionally devastate the groups to the eastward. The period of the westerly winds in the Solomon Islands is also characterised by calms and variable winds. The exhilarating freshness of the Trade then gives place to the enervating influence of the Monsoon; and, in consequence, the period of westerly winds is the sickly season.

RAIN-REGISTER AT SANTA ANNA.

(Kept by Mr. Charles Sproul[503] between October 25th, 1882, and December 31st, 1883.)

The rain-gauge used was of the common round funnel pattern (5·7 inches). The observations were made at Port Mary on the west side of the island. The elevation of the guage was some four or five feet (or less) above the high tide level.

MONTH.	Total in inches and hundredths.		Number of rainy days.[504]		Greatest daily fall.
1882.
October, 25th-31st		3·06		5	1·70
November		7·06		15	1·97
December		13·96		24	2·24
	Total,	24·62	Total,	44
1883.
January		5·23		12	2·03
February		9·63		20	2·00
March		4·40		13	·84
April		14·96		24	3·22
May		11·28		16	3·33
June		26·88		19	7·73
July		18·61		23	3·45
August		11·74		15	2·02
September		4·81		12	2·52
October		5·68		9	1·67
November		6·57		11	1·20
December		5·24		8	1·68
	Total,	125·03	Total,	182

Results for 1883.—Total rainfall for 1883; 125·03 inches. Two-thirds of the total fall, i.e., 83·47 inches, were recorded during the five months from April to August. Greatest daily fall, 7·73 inches. Total number of rainy days 182, i.e., one half of the year. On 41 days, more than an inch of rain fell.

RAIN-REGISTER AT UGI.

(Kept by Mr. Fred Howard between October 1st, 1882, and December 31st, 1883.)

The rain-gauge used was of the round funnel pattern (about 5¹⁄₂ inches). The observations were made at the residence of Mr. John Stephens at Selwyn Bay on the west side of the island. The elevation of the gauge was from four to six feet above the high-tide level.

MONTH.	Total in inches and hundredths.		Number of rainy days.	Greatest daily fall.	Relative humidity taking 100 as saturation (see table, p. 367)
1882.
October		10·68	18	2·45
November		10·16	16	4·60
December		9·57	21	1·36
	Total,	30·41	55
1883.
January		13·46	16	5·75	(83)
February		13·89	17	4·00	82
March		10·02	16	3·00	83
April		23·28	26	3·00	88
May		6·39	9	1·65	83
June		12·83	12	3·70	84
July		24·60	25	2·85	89
August		15·76	15	4·75	83
September		7·36	14	1·50	81
October		5·15	7	1·75	76
November		5·30	11	1·10	79
December		8·20	10	1·30	83
	Total,	146·24	178

Results.—During the last quarter of 1882, the rainfall was 30·41 inches; and the number of rainy days was 55.

During 1883, the total rainfall was 146·24 inches. The greatest monthly records were those of April and July: during these two months 47·88 inches fell, or about one-third of the total fall for the year. The greatest daily fall was 5·75 inches. The total number of rainy days was 178, or about one half of the number of days in the year. On 56 days more than an inch of rain fell; and in 18 days more than two inches fell.

RAIN-REGISTER KEPT ON BOARD H.M.S. “LARK.”

(I am indebted to Lieutenant Leeper for assistance in keeping this register.)

The rain-gauge was raised about eleven feet above the water-level. I did not commence these observations until towards the close of the first season; and since, during the two following years, we spent about two-thirds of each year in this region, the record is, in consequence, not continuous.

(A) OFF THE NORTH COAST OF ST. CHRISTOVAL AND THE NEIGHBOURING ISLANDS IN 1882.

1882.	Total in inches and hundredths.	Number of rainy days.	Greatest daily fall.
Sept. (from the 9th),	18·40	15	3·32
October,	10·84	21	2·38
Nov. (to the 21st),	18·31	12	5·74
Total,	47·55	48

Results.—Total Rainfall for this interval of 74 days from Sept. 9th to Nov. 21st, 1882, was 47·55 inches. The greatest daily fall was 5·74 inches. The number of rainy days was 48, or about two-thirds of the whole. On 17 days, more than an inch of rain fell; and on 8 days, more than two inches fell.

(B) OFF THE NORTH COAST OF ST. CHRISTOVAL AND THE NEIGHBOURING ISLANDS IN 1883.

1883.	Total in inches and hundredths.	Number of rainy days.	Greatest daily fall.
April 13th-30th,	10·43	15	1·62

(C) BOUGAINVILLE STRAITS IN 1883.

1883.	Total in inches and hundredths.	Number of rainy days.	Greatest daily fall.
June,	16·32	26	2·23
July,	10·25	24	2·12
August,	7·78	23	1·10
September,	15·07	22	2·20
October,	11·01	25	2·10
Total,	60·43	120

Results.—During these 153 days, there fell 60·43 inches of rain. The greatest fall in one day was 2·23 inches. The total number of rainy days was 120, or about four-fifths of the whole. On 14 days, more than an inch of rain fell; and on 7 days, more than two inches fell.

(D) BOUGAINVILLE STRAITS IN 1884.

1884.	Total in inches and hundredths.	Number of rainy days.	Greatest daily fall.
April (from the 8th),	7·82	12	4·32
May,	4·02	17	1·02
June,	9·22	22	1·58
July,	18·16	19	8·09
August,	11·87	21	2·58
September,	17·46	23	3·76
October,	10·95	23	1·84
Total,	79·50	137

Results.—During these 207 days, there fell 79·50 inches of rain. The greatest daily fall was 8·09 inches. The total number of rainy days was 137, or about two-thirds of the whole. On 24 days, more than an inch of rain fell; and on 7 days, more than two inches fell.

OBSERVATIONS[505] OF THE BAROMETER AND THERMOMETER IN THE SOLOMON GROUP, BY LIEUT. LEEPER, R.N.

(Taken on board H.M.S. “Lark.”)

	THERMOMETER.			BAROMETER.
MONTH.	Highest.	Lowest.	Daily Mean.	Highest.	Lowest.	Daily Mean.
1882	°	°	°	In.	In.	In.
April,	94	74	84·4	30·09	29·88	30·041
May,	94	78	84·5	30·09	29·89	29·994
June,	92	77	83·7	30·18	29·86	30·013
July,	90	75	81·8	30·14	29·92	30·05
August,	94	75	81·1	30·16	29·96	30·067
September,	92	76	80·9	30·14	29·93	30·041
October,	89	77	81·4	30·18	29·88	30·021
Nov. 1st to 22d,.	88	78	81·5	30·13	29·84	29·981
1883
April 14th to 30th,	92	75	82·1	30·08	29·86	29·974
May,	...	...	...	...	...	...
June,	93	78	81·8	30·08	29·91	29·99
July,	94	75	82·3	30·12	29·88	29·96
August,	92	78	83·5	30·08	29·92	29·992
September,	95	76	82·6	30·10	29·91	29·992
October,	95	75	83·3	30·12	29·86	29·993
Nov. 1st to 12th,	90	76	81·5	30·08	29·91	29·982
1884
April 5th to 30th,	90	76	82·2	30·15	29·83	29·984
May,	95	78	84·5	30·13	29·86	29·992
June,	94	77	82·2	30·14	29·93	30·023
July,	87	76	81·5	30·10	29·87	29·985
August,	87	76	81·0	30·15	29·85	30·009
September,	90	75	82·3	30·15	29·92	30·025
October,	96	75	81·1	30·12	29·85	30·007

Results calculated from observations of the temperature in the shade, and of the wet and dry bulb thermometers taken at Ugi at 9 a.m., by Mr. F. Howard.[506]

THERMOMETER IN SHADE.				HYGROMETER.[507]
MONTH.	Highest.	Lowest.	Mean.	Mean Dry Bulb.	Mean Wet Bulb.	Mean Dew Point.	Mean Elastic Force of Aqueous Vapour.	Mean Relative Humidity, Saturation 100.
1882.
October	87	76	81·7	...	...	...	...	...
November	84	78	80·5	...	...	...	...	...
December	84	80	81·4	...	...	...	...	...
1883.
January	86	79	82·0	...	...	...	...	...
February	85	79	81·5	81·6	78·0	75·6	·885	82
March	86	78	81·8	81·7	78·3	76·0	·898	83
April	83	76	80·0	80·1	77·8	76·2	·904	88
May	85	78	81·6	81·6	78·2	75·9	·895	83
June	84	77	80·6	80·6	77·5	75·4	·880	84
July	83	77	80·2	80·2	78·0	76·4	·912	89
August	84	77	80·3	80·3	76·9	74·6	·857	83
September	84	77	80·9	80·9	76·9	74·2	·846	81
October	85	76	82·0	82·0	77·0	73·6	·830	76
November	86	77	82·0	82·0	77·8	74·9	·867	79
December	84	79	81·3	81·4	78·0	75·7	·891	83
81·2—Mean for 1883.

WIND-RECORD FOR EACH MONTH.

Prepared from the observations taken on board H.M.S. “Lark,” and by Messrs. Sproul and Howard, at Santa Anna and Ugi.

January.

1883. At Ugi, S.W. to W. in first half; variable in latter half; S.E. 1 day. At Santa Anna, N.W. and W.; S.E. 5 days; occasional squalls.

February.

1833. At Ugi and Santa Anna, N.W. to S.W.; no S.E.; latter part, fresh winds and squalls.

March.

1883. At Ugi and Santa Anna, N.W. to W. in first half, with strong winds and thunderstorms; latter part variable; S.E. 4 days at Ugi, none at Santa Anna.

April.

1882. Amongst the eastern islands (east of Florida); first part, calms and light northerly winds; latter part, calms and light S.E. winds; thunderstorms frequent.

1883. At Ugi and Santa Anna, first part, N.W. and S.E.; latter part, calms and E. to S.E.; S.E. for 7 days at Ugi; heavy rain; squalls in middle of month.

1884. In Bougainville Straits, light northerly and westerly winds, with calms; easterly during the last few days.

May.

1882. Between Bougainville Straits and west end of Guadalcanar, numerous calms and light winds from N.W. through S. to S.E.; thunderstorms frequent.

1883 At Ugi and Santa Anna, E. to S.E.; usually strong.

1884 In Bougainville Straits, light N.E. and easterly winds, with a great deal of calm weather.

June.

1882. At the north coast of St. Christoval, Ugi, and Santa Anna; calms, N.N.E. and easterly winds; average force 2.

1883. At Ugi and Santa Anna. S.E. often strong, with variable winds.

In Bougainville Straits; first part light E. and S.E. winds; latter part, S.E.; very squally; frequent thunderstorms.

1884. In Bougainville Straits; first half, light E. and E.S.E. winds; latter half, light S.E. and S.S.E.

July.

1882. At the north coast of St. Christoval and Ugi, first part S.E., with frequent heavy squalls; latter part, light S.E. and S.W. winds, though squally.

1883. At Ugi and Santa Anna, E.S.E. to S.E.; fresh and squally, sometimes blowing hard, interrupted by calms and varying winds.

In Bougainville Straits, light varying winds from N.E. to S.E.

1884. In Bougainville Straits, first part light S.E. winds and calms; latter part fresh easterly winds and bad weather.

August.

1882. At the north coast of St. Christoval and Ugi, E.N.E. to S.; average force, 3 to 4; frequent rain-squalls.

1883. At Ugi and Santa Anna, S.E. strong; in latter part heavy squalls, interrupted by calms.

In Bougainville Straits, E.N.E. to S.E.; force 2 to 3.

1884. In Bougainville Straits, S.S.E. to S.; thick weather with rain-squalls in first part.

September.

1882. At Ugi and the Three Sisters, S.E. and S.S.E.; in latter part of month heavy, and accompanied by thick weather and violent squalls.

1883. At Ugi and Santa Anna, E.S.E. to S.E. strong. In Bougainville Straits, calms, and light E. to S.E. winds.

1884. In Bougainville Straits, first part light S.E. winds and heavy rain-squalls from N.E.; latter part fresh S.S.E. and dirty weather, followed by light N. to E. winds.

October.

1882. At Ugi, Santa Anna, and off the north coast of Guadalcanar; in first part, strong S.E.; in latter part, easterly winds with calms. At Ugi, S.E. in first half, variable with calms in latter half.

1883. At Ugi and Santa Anna, S.E., fresh. In Bougainville Straits, first part S.E. to S.; latter part N.E. to S.E., squalls and thunderstorms.

1884. In Bougainville Straits; first week, light N.E. to S.E. winds; second week, S.S.E. to S., force 2 to 4; third week, N.W. to N.N.E., force 3 to 8, rain-squalls and thunderstorms; last part, variable and E.S.E. winds.

November.

1882. At Ugi and Santa Anna; first half, N.W. and S.E.; latter half, S.E. and variable.

1883. At Ugi and Santa Anna, fresh E.S.E. to S.E; northerly towards end of month with squalls and thunderstorms.

December.

1882. At Ugi and Santa Anna, westerly and variable; S.E. for 6 days: latter part, squally.

1883. At Ugi and Santa Anna; in first half, E. to S.E.; in latter half, N.W. to S.W. and squally.

THE EFFECTS OF THE CLIMATE ON THE WEIGHT OF THE BODY.

During the last two surveying-seasons in these islands, the officers and crew were weighed with the object of determining the effect of service in this climate on the body-weight. The period spent in this region during each year extended from April to November.

After eliminating various sources of error, such as sickness, immaturity, etc., I find that during the surveying-season of 1883, which occupied between 6¹⁄₂ and 7 months, eighteen out of twenty persons lost weight, the average loss being 6³⁄₄ lbs., and the range of the loss 1 to 12 lbs. Of the two exceptions, one gained 3 lbs. and the other experienced no change. On returning to the colonies, we spent between 3 and 4 months in the genial climate of northern New Zealand, at the end of which period I find that the average gain of weight was about 6¹⁄₂ lbs. In other words, the loss was regained.

During the season of 1884, which lasted 7 months, eleven out of the twenty persons weighed in the previous year were alone available for these observations. All of them lost weight, the average loss being 5³⁄₄ lbs., and the range 1 to 8 lbs. This diminution in the average loss of weight during this season should be noted. . . . . I should add that five individuals, who had not been on board in the previous year, lost during this season on the average 5 lbs. per man.

I may therefore conclude that the effect of seven months’ service in this region on the body-weight is, on the average, a loss of from 6 to 7 lbs. Although this loss of weight is mainly attributable to the climate, it is evident that the character of the diet has an important influence in the matter. For the greater part of the time spent in these islands, the crew were on preserved and salt rations, a diet which reduces the weight of the body. One of the results of an elaborate series of observations made by Dr. A. Rattray of H.M.S. “Salamander,” whilst serving in the Western Pacific from 1864-67, was to show that salt diet in a tropical climate is an important factor in reducing weight, and that other influences, such as that of hard work, increase the loss. During various cruises in the tropics, usually lasting about three months, he weighed between 70 and 100 men with the following results. The effect of a tropical climate alone was to reduce the weight of 64 per cent., the average loss being 5 lbs. When the unfavourable conditions of a wet season and salt diet were added, 76 per cent. lost weight, the average loss being 7 lbs. By the further addition of hard work, 91 per cent. lost weight, the average loss being about the same. The loss of weight after each cruise was regained in 7 or 8 weeks during the stay in Sydney.[508]

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