Our boat was fitted with two masts, a mainmast and a mizzen or dandy mast. The former was 6 feet long and the latter 4 feet long, and each measured 1-1/2 inches in diameter at the base, tapering to about 1 inch diameter at the upper end. They were held in brass bands, or clamps, bent around them and secured to the bulkheads, as shown in Fig. 117. The sails were of the lanteen type.
Fig. 118. The Mainsail. The mainsail measured 8-1/2 feet along the boom, 9-1/2 feet along the yard and 10 feet at the leach. The dimensions of the mizzen sail were: along the boom, 5 feet; along the yard, 5-1/2 feet; and at the leach, 6 feet. The boom was attached to a strap of leather on the mast, and was thus given freedom to swing around in any desired position. The yard was similarly attached, and was raised
Fig. 119. The Mizzen Sail. by a cord, which passed through pulleys at the top and at the base of the mast and extended to a cleat within easy reach of the occupant of the boat. A double paddle was fashioned from a board 1 inch thick, 6 inches wide and 6 feet long. The blades were shaved down to a thickness of 3/8 of an inch at the edges.

A canoe is rather a tipsy thing to sail in, as we soon learned, and it was lucky that we could all swim, else our vacation
Fig. 120. The Double Paddle. might have ended very tragically; for the very first time Bill and I tried the boat an unexpected gust of wind struck us and over we went. We were very poor sailors at first, but it didn’t take us long to catch on.

One thing that bothered us greatly in sailing was the keel of our canoe. It was forever getting twisted, particularly when we tried to make a landing. There were only a few places along the island where the water was deep enough to permit our coming right up to shore without striking the keel. The fastening was not very strong, and every once and awhile it would be wrenched loose. The matter was made the subject of a special letter to Uncle Ed, and in due time his answer was received. As usual, he offered a first-class solution of the difficulty. “Don’t use a keel,” he wrote; “lee boards are much better.” Then he went on to explain what was meant by lee boards: “The leeward side of a boat is the opposite of the windward side; that is, that side of the boat which is sheltered from the wind. Lee boards, then, are boards which are hung over the lee side of a boat to prevent it from drifting to leeward, and they serve to take the place of a keel or centerboard.”

Following Uncle Ed’s direction we fastened a strip of wood across the canoe about six feet from the bow, nailing it firmly to the gunwales. This provided a support to which the lee boards were secured. The lee boards were paddle-shaped affairs of the form and dimensions shown in Fig. 121. Each paddle near the top was hinged to the end of a board three inches wide and a foot long. The paddle was held at right angles to the board by means of a hook. Each board was fastened
Fig. 122. Section of the Canoe, Showing Lee Board. with door hinges to a baseboard which extended the width of the boat and was attached to the crosspiece of the canoe by means of a couple of bolts. The bolt heads were countersunk, so that the hinged boards could lie flat over them. To the top of each lee board two ropes were attached, one passing forward around a pulley and thence back to a cleat within easy reach of the occupant of
Fig. 123. The Lee Boards in Use on Canoe. the canoe, and the other passing directly back to this cleat. By pulling the former rope the lee board was lifted out of the water, while the latter rope was used to swing the board into working position. When tacking to port (left), the board on the left side of the canoe was lowered and the other was raised, as shown in Fig. 123, and when tacking to the starboard (right) the board on the right side was lowered, while the left one was raised.

Our sailing canoe proved such a good one that we decided to build a second. This was to be much lighter, for paddling only, and of the true Indian shape, with wide, bulging sides and raised stem and stern. The dimension of the
Fig. 125. Intermediate Form. forms used are given in Figs. 124 and 125. These forms, it will be observed, were notched to receive the keelson and
Fig. 126. The Stem Piece. gunwales. The keelson was formed of 1-inch spruce 3 inches wide and 10 feet long. The stem and stern, which were both of the same shape, were cut from a 12-inch board to the form shown in Fig. 126, and were firmly secured to the keelson. This made the boat 12 feet long. The forms were then set in place on the keelson, one at the center and the others three feet each side. The gunwales were formed of 3/4-inch by 2-1/2-inch spruce, and the twelve rib bands used were of the size used in our first boat. As none of these forms was to remain in the boat, nails were driven very
Fig. 127. Skeleton Frame of Canoe. lightly into them, with heads projecting so that they could easily be withdrawn when it was time to remove the forms. The cross ribs were passed under the keelson inside of the rib bands and outside of the gunwales, as shown in Fig. 128. After they were set in place and firmly secured with copper tacks, a band was nailed to the keelson to form the keel. To produce the raised stem and stern, four wedge-shaped pieces were nailed to the tops of the gunwales, as indicated in Fig. 129. The
Fig. 128. Section at Center of Canoe. forms were then removed and were replaced with cross sticks braced between the gunwales. The center cross stick was provided with two corner pieces, as shown in Fig. 130, adapted to fit under the gunwales and against the rib bands. The canvas was then applied in the manner described before, but was tacked to the upper edge of the gunwale instead of the outer side, and the tacks were covered by a half-round molding which extended around the entire boat. After the lacing was cut the edge of the canvas was secured to the under edges of the gunwales. The canoe was then completed by fastening on a 1-inch square keel and treating the boat with two coats of paint. The paddle was a duplicate of the one described in connection with the sailing canoe.

CHAPTER XI.
HOUSE BUILDING.

The grass lodge appealed to us as very picturesque, and we set to work immediately on its construction. We made our hut much smaller, however, only 12 feet in diameter, and 8 or 9 feet high. First we procured two dozen light poles between 10 and 12 feet long. These we set up about 18 inches apart in a circle like a stockade, the sticks being buried in the ground to a depth of 12 inches. At one side a space of 3 feet was allowed for a doorway. Inside the stockade we erected a working platform of planks supported on barrels, and standing on this we took two opposite poles, bent them inward and lashed
Fig. 132. Doorway of the Hut. their upper ends together. Then a second pair of opposite poles were similarly bent inward and tied, and so we proceeded until the entire stockade had been converted into a dome-shaped cage. Around these poles we laid lighter sticks, or bands, tying them at the points of intersection. At the doorway two posts were set firmly in the ground, projecting upward to a height of 4 feet. A lintel nailed across the top of the posts completed the door frame. Sticks were nailed to the lintel and to the side posts, extending to the main frame of the hut, to which they were tied. We were now ready to thatch our hut. Reddy and Dutchy went over to Lumberville for several bales of straw. We tied the straw in bunches and applied it to the frame, copying, as best we could, the process illustrated in the photograph.

But for its location the hut would have proved a very serviceable habitation. In order to have a good, dry dwelling without laying down a board flooring, we had selected for its site the sandy shore at Point Lookout. This part of the island was not sheltered with trees, and the hot sun beat down on our hut so strongly that we found the quarters very uncomfortable indeed. It was this fact that led to the construction of a tree hut–a building that would be perfectly dry and yet shaded and cool. Bill had read of such houses in the Philippines and felt confident that we could build one. We couldn’t decide at first where to locate our hut until Dutchy moved that we build it in the gnarled oak tree overlooking the “Goblins’ Dancing Platform.” Immediately the motion was seconded and unanimously carried.

The Goblins’ Dancing Platform.

Just above the town of Lumberville there was a cliff which rose sheer 200 feet above the level of the river. So perpendicular was the cliff that a stone dropped from the overhanging ledge at the top would fall straight down to the railroad track below without touching a twig in its course. Back of this broad ledge there was a very peculiar formation. A column of stone rose abruptly 40 feet higher and was topped with a large slab about 12 feet in diameter. This was known all over that region as the Goblins’ Dancing Platform. The only possible way of gaining the summit of the column was by climbing a scraggly oak tree which grew on the high ground back of the pillar, crawling out on an overhanging limb, and then dropping down to the platform below. It was in this oak that we decided to build our house. It was a very inaccessible spot, and to reach it we had to make a wide detour around the back of the hill, and through the fields of a cranky farmer, who more than once threatened to fill us with bird shot for trespassing on his property. How were we to carry all our building materials up to this great height? One would think that the difficulties would be enough to discourage us, but not so with the S. S. I. E. E. of W. C. I. Nothing daunted us.

Dutchy Takes a Dare.

Our first task was to try some other approach to the top of the cliff. At one side of the overhanging ledge there was a fissure in the rocks which ran from the base of the pillar to the foot of the cliff. Down this zigzag crevice Dutchy had scrambled, one afternoon, on a dare. We were rather frightened when he started, because it was a very hazardous undertaking, and we watched him anxiously, peering over the edge of the precipice. By bracing his back against one of the walls of the rock, and digging his feet into the niches and chinks of the opposite wall, he safely made his way to a shelf about half-way down, where he paused to rest. From that point on the fissure widened out, and a steep, almost vertical incline, sparsely covered with vegetation, led to the railroad track below. I think he must have become rather frightened at his position, because he hesitated long before he resumed his downward course, and when he finally did make the attempt his foot slipped upon the moss-covered rocks and down he fell, scratching and clawing at every shrub within reach. Believing him to be killed, we rushed down the hill and around to the foot of the cliff. It probably took us about fifteen or twenty minutes, though it seemed ages before we came upon our venturesome comrade coolly trying to pin together a rent of inconvenient location and dimensions in his trousers.

“Say, Dutchy, are you killed?” cried Bill, breathlessly.

“Killed, nothing,” he replied, with scorn. “I suppose you fellows think I had a fall. Well, I didn’t.”

“You didn’t, eh? We saw you slip.”

“Oh, go on. I came down that way on purpose. There was no use in picking my way down like a ’fraid cat, when I could just as well take a smooth and easy toboggan slide on the bushes all the way down.”

Smooth and easy toboggan slide! Well, you should have seen the hillside. The course was well defined by the torn and uprooted shrubs and the pile of branches and vines at Dutchy’s feet. Whether the hare-brained Dutchy really imagined he could glide easily down on the shrubbery, his frantic movements on the way certainly belied his story, and when, the next day, we proposed that he repeat the trick, somehow he didn’t seem to be very enthusiastic on the subject.

It was up this fissure that we decided to haul materials for our tree hut. Our first task was to build steps and ladders in the steepest parts. We had no tool for cutting out niches in the rock, but wherever natural depressions were formed we wedged in sticks of wood between the side walls to serve as ladder rungs. If no such niches appeared for considerable height, we would stretch a rope ladder to the next fixed rung. In most places the natural formation of the rock was such as to afford sufficient footing.

Rope Ladders.

The rope ladders were made of two parallel side straps, tightly stretched between the fixed sticks, and then at intervals of fifteen inches we inserted the ends of the ladder rung between the strands of the rope. Below and above each rung the rope was bound with cord. The rungs were notched at the ends to prevent them from slipping out.

After providing a means for scaling the cliff (we called it the Jacob’s Ladder), we were still confronted with the problem how to cart our building materials to the top. It was a very hard task and you couldn’t have hired us to do it under any other circumstances. First, Bill planned out on
Fig. 136. The Derrick. paper just how the house was to be built, and we cut all the pieces to the right size so as not to carry up any superfluous matter. When all was ready the boards and sticks were loaded on the scow, and ferried over to the cliff. Then we carried them on our backs, three or four at a time, up the slanting hillside to the first ledge. From there up, owing to the steepness of the ascent, we had to employ different tactics.

The Derrick.

A derrick was constructed of two sticks 10 feet long, which were bolted together at the top, and secured about five feet apart at the bottom by a cross piece, as shown in Fig. 136. The derrick was then taken apart and with some difficulty hauled piecemeal up to the next ledge above. Here it was put together again. The fall and tackle used in our aerial railway was attached to the apex of the derrick, and the latter was then erected with the legs set into depressions in the ledge and the upper ends slanting outward but kept from falling over the edge by a rope tied to one of the fixed rungs set in the fissure. With this derrick we hoisted up the boards in a few hauls. The job was a very ticklish one, but Bill used the greatest care to prevent accident. The derrick, rope and tackle were carefully tested before used, and as soon as the load was attached to the lower pulley block the two who did the loading were instructed to crawl back into the fissure so as to be out of danger in case anything gave way. At one time a stick which had been carelessly tied did fall, and it might have badly hurt some one had we not observed this precaution. When we had raised the material to the second ledge we transferred operations to the top ledge, and when the materials had been hauled up to this point we finally rigged up our fall and tackle in the old oak tree itself.

The Tree House.

The tree had two large limbs which extended out at a wide angle from the main trunk. Across these two limbs, at about seven feet out, we laid our first girder, nailing it securely in place. Then to the main trunk we nailed the second girder on a level with the first. Diagonal braces were extended from the trunk to support the ends of this girder, and a tie piece was nailed to the braces, as shown in Fig. 138, to prevent them from spreading. The girders were rough sticks about 4 inches in diameter and 10 feet long. We cut flat faces on them at the points where they were nailed to the tree, and then, to make them doubly secured, we nailed cleats, or blocks of
Fig 139. Top View of the Platform. wood, to the tree under them. The floor beams were then laid across and nailed to the girders. They were cut to a length of 10 feet so as to project beyond the outer girder to provide for a piazza overhanging the Goblins’ Platform. Six floor beams were used, spaced 20 inches apart. All branches projecting up between the beams were then cut away and a flooring of slabs was laid on. To the main trunk six feet above the flooring, a stick or (to use the technical term), “wall plate,” was nailed on, and its ends were supported by upright posts resting on the platform. Thirty inches from the outer end of the platform two more posts were erected eight feet high and secured by sticks nailed across from the other posts, and also by a second wall plate connecting their upper ends. Four more posts were erected, one between each pair of the corner posts, and then we were ready to enclose the framing.

The sidewalls were first clapboarded, because we were afraid the roof would not hold us until the framing had been strengthened by nailing on the siding. Slab boards were used for this purpose. Beginning at the bottom, the boards were laid on, each lapping over the one below, as shown in Fig. 141, so as to shed water. In each side we
Fig. 141. Nailing on the Clapboards. cut a window opening and nailed on a window casing of the type shown in Fig. 142, which will be described in a moment. As soon as the clapboards were applied, we nailed on the rafters and then applied the roofing. The same principle was here used for shedding water. The lowest board was first laid on, and then the others were successively applied, each lapping over the one below.

The window casings we used each consisted of a frame about 15 inches square, but with the upper and lower pieces extending 12 inches beyond one of the side pieces. On these extended pieces a slideway was formed for the
Fig. 143. The Window Sash. window sash by nailing on two strips of wood about 3/4 inch square and over them a pair of wider strips projecting inward, so as to overlap the edges of the sash. The window sash consisted of a frame 13-1/2 inches square, made of 3/4-inch square strips over which canvas was tightly stretched and tacked. A spool was nailed on at one side for a handle. These windows were closed only in rainy weather, to keep the water out.

Sliding Doors.

We had two doors; one at the back of the house, from which a ladder extended down to the ground, and another opening out onto the veranda, from which we dropped a ladder down to the Goblins’ Dancing Platform. In order to save space we used sliding instead of swinging doors. The back door frame was 5-1/2 feet high and the front door frame 6 feet high. The doors were mounted on the outside of the building. The side posts of each frame were 2-1/2 feet apart, and the lintel and sill extended 3 feet beyond the side post at one side. The upper face of the lintel was planed down perfectly smooth, and its edges were tapered off to make a track for the rollers on the door. The rollers consisted of two spools, which turned on tenpenny nails driven into the top of the door. At the lower end two more spools were mounted, turning on nails driven in the bottom edge of the door. The rims of the spools extended slightly beyond the outer face of the door and rolled against the sill. To keep the water from leaking in at the top a slanting board was fastened above it, as shown in Fig. 144. The back door was similarly constructed. Our tree house was completed by a running balustrade around the veranda.

It strangely happened that just after our tree house had been built we received a photograph from Uncle Ed of a Filipino tree house made of bamboo.

CHAPTER XII.
TROUBLE WITH THE TRAMPS.

We were a proud lot when the house was finally completed. From the veranda we had an excellent view up and down the river. We could see our camp on the island and keep watch of our goods. Late one afternoon Dutchy and I were lolling about on the Goblins’ Platform, idly watching a hawk soaring above us. The rest of the boys had returned to the island in canoes an hour before and left the heavy scow for us to row back. It was drawing near supper time and we had about decided to start for home, when I chanced to see a scow up the river. It looked exactly like ours, and in it were two men, evidently drunk, from the way they carried on. A glance showed me that our scow was not at its moorings. How were we to reach the camp? One of the men had evidently seen us and was pointing us out to his companion. We rushed down the Jacob’s Ladder, but by the time we reached the river bank they were in midstream and heading rapidly northward. Our shouts merely brought forth derisive laughter. We were certainly in a predicament. First we ran back up the cliff, and tried from there to gain the attention of the rest of the fellows. They evidently saw us but couldn’t make out what we wanted. Then we ran down to a point opposite the island and called to them. But the wind was against us and we couldn’t make them hear, so we had to plunge in and wade across.

A Council of War.

Immediately we summoned a war council. Dutchy and Jack were chosen by lot to guard the camp, while the rest of us started in pursuit in canoes. By the time we got under way the sun had dropped back of the Pennsylvania hills and the shadows were climbing slowly up the Jacob’s Ladder. Swiftly we paddled up-stream, keeping close to the western shore, where the water was very quiet. We didn’t expect to go far, because there were rapids less than three miles up, and we were sure that no tramps would ever be ambitious enough to row a heavy scow against the swift current at that point. As we rounded a sharp bend in the river, we noticed a camp fire a few hundred feet further up, around which five or six men were lounging, and there, just below them, was our scow. What were four boys to do against six grown men? We were each armed with a club, and could have made a pretty good fight if necessary, but after a whispered consultation we decided it would be best to wait until dark, when we could creep up quietly and steal away unnoticed with our boat.

Vengeance.

It seemed as if darkness never would come. It was scarcely dusk when our patience gave out and we paddled up stealthily, hugging the shore. Bill gained the scow unnoticed, but just as he was about to push off he discerned the body of a man within. It was one of the tramps lying there in a drunken stupor. What was to be done? Every moment was precious. A yell from the fireside decided him. With a mighty push he launched the boat out into the current, while we threw him a line and towed the boat out to midstream. With a volley of curses the men sprang up and pelted us with stones. But they were poor shots, and we escaped without serious injury. Our prisoner, in the meantime, was snoring heavily in the scow undisturbed. We took him down-stream and then unceremoniously picked him up and dumped him overboard within a few feet of the shore. It was a rude awakening, and nearly frightened the wits out of the man. But it brought him to his senses, and in a moment we were dodging more stones, sent with such good aim that we had to lie flat in the bottoms of the boats until the current carried us out of reach.

A Double Surprise.

It was now quite dark, and we had some difficulty in groping our way back to camp. There was no moon and the stars were obscured by clouds. Our only course was to follow the shore line until we got around the bend, and then we steered for the beacon fire, which, by prearrangement, had been kindled on Point Lookout. But the spirit of mischief was in us. We thought we would have some fun with Dutchy. We could see him silhouetted against the blaze. Jim and I hung back in the canoes, while Reddy and Bill went on with the scow, splashing their oars and shouting and singing in disguised voices, like drunken men. Dutchy was evidently very much agitated. His “Hello, there! Boat ahoy!” was greeted with derisive yells.

We had a merry laugh over the situation when suddenly the tables were turned. Something whizzed past Bill’s ear; I was stung on the arm with a heavy nail; a large stone hit the scow; Reddy had his hat knocked off, and Fred upset his canoe trying to duck out of reach of the invisible missiles before we could make our assailants understand that we were friends and not the tramps. The joke was on us after all. We hadn’t counted on Dutchy’s accurate aim or Jack’s skill with the crossbow.

Tramp-proof Boat Mooring.

Around the camp fire that night we discussed our adventures and made plans to prevent their recurrence. It was evident, for one thing, that we would have to moor our boats off shore in such a way that they would be out of reach of meddlesome persons, and yet could be drawn in toward shore by any one who knew how. This was the way we did it. A pair of galvanized iron ring bolts were procured on Jack’s next trip to Lamington for provisions, also a light rope about forty feet long. The ring bolts were screwed into a pair of stout anchor stakes about two feet from their lower ends. The rope was passed through the rings and the ends were joined by tying them to a galvanized iron link. Then it was soaked for a while to shrink it before it was set in place. After the rope had shrunk sufficiently, the two stakes were driven into the bed of the river, one close to the bank and the other far enough out to hold the rope belt clear of the bottom. Both stakes were sawed off under water, just above the ring bolts, so that they were hidden from sight. When we wanted to moor our boats we secured their anchor ropes or “painters” to the link. A large stepping stone marked the spot were the inner stake was driven, and standing on this stone we were able to reach down and haul in on the lower strap of the belt to draw the boat out a safe distance from shore, and then when we wanted to use our boat again we would haul in the upper strap to draw the boat in toward shore.

CHAPTER XIII.
WIGWAGGING AND HELIOGRAPHING.

There were only three different movements that could be made with flags, but in the book different combinations of these movements were given to represent each letter of the alphabet and the numbers from 1 to 0. All these movements were begun and ended by holding the flagstaff upright, directly in front of the body, as shown in Fig. 147. The first movement was to swing the flag down to the right and back (Fig. 148), the second to the left and back (Fig. 149), and the third forward and back (Fig. 150). The following table gives the different combinations used for various letters:

The Wigwag Alphabet.

Numerals.

The numbers 1, 2 and 3 indicate respectively the first, second and third movements. For instance, A was represented by the combination 22,
Fig. 151. The Signal for Letter “B.” which means that the flag must be swept to the left and back twice. B is represented by the combination 2112, that is, a sweep to the left, two sweeps to the right and a final sweep to the left, as shown in Fig. 151. The end of a word was represented by a sweep forward and back; the end of a sentence by two sweeps forward and back, and the end of a message by three sweeps forward and back. It will be noticed that the same combinations are used for 2 and Z, 3 and tion, 4 and F, 5 and J, 6 and G, 7 and V, 9 and M, and 0 and B. The following abbreviations were given in the Manual:

These abbreviations saved a lot of time, for when we wanted to signal the word after instead of spelling it out–22-2221-2-12-211-3–we used the signal for A–22–followed by 3 to signify that it was the end of the word. Before was represented by 2112-3, your by 111-211-3, etc. It took quite a little practice to learn the different combinations. Fred and Reddy soon became experts, and could flash the signals back and forth at a great rate.

Wigwagging at Night.

The book that Uncle Ed sent us had in it a description of a heliograph, that is, an instrument for sending signals with flashes of sunlight. Although our wigwagging system was good enough for our requirements, yet we thought it would be more scientific to use the sun instrument, and besides, the latter could be used for signaling many miles.

The Single Mirror Instrument.

The first thing we did was to procure a small mirror about 4 inches square, mounted in a wooden frame. Then we got
Fig. 153. Trunnion for Mirror. a pair of small square head bolts about 1/4 of an inch in diameter and 1 inch long, also two strips of brass 1/2 inch wide and 3 inches long. In the center of each brass strip we drilled a hole just large enough to admit the shank of one of the bolts, and then the strips were fastened with screws tight against opposite edges of the mirror frame, with the heads pressed against the frame and the shanks sticking out at each side, as shown in Fig. 153. These projecting shanks served as “trunnions” (that is, pivots) for the mirror to turn on when it was mounted in place. After the trunnions had been set in place we made a peep hole in the center of the mirror by cutting out a piece of the wooden back of the frame and scratching away the silver from the back of the glass. Only a very small hole was required, about 1/8 inch in diameter. Great care was taken to have the unsilvered spot exactly on a line with the trunnions and just half-way between them. This done, we took two sticks
Fig. 154. The Single Mirror Instrument. of 3/8-inch wood, 1 inch wide and 3-1/2 inches long. In the upper end of each stick a slot was cut 1/2 inch deep and 1/4 inch wide. Into these slots the trunnions of the mirror were placed, and then the nuts were screwed tightly on, clamping the sticks against the sides of the mirror. The sticks were now connected by nailing a 1/2-inch strip at the bottom, and braced by a couple of corner pieces. This formed a swiveled frame for the mirror, which was clamped to the base of the instrument by means of a bolt 1-1/2 inches long. The bolt passed through the bottom board of the frame, squarely under the peep hole of the mirror and through the baseboard of the instrument near one end. The baseboard was 2 inches wide, 10 inches long and 3/4 inch thick.

At the end opposite to where the mirror frame was swiveled we mounted a sight rod, which was merely a round stick of wood 1/2 inch in diameter and about 8 inches long. We cut the stick from one of the rounds of an old broken chair. The upper end
Fig. 155. The Sight Rod. of the rod was whittled to a point and one side was flattened as shown in Fig. 155. Out of a piece of heavy white cardboard we cut a round disk about 1/4 inch in diameter, with a shank 1 inch long sticking out at one side. This was fastened with a single tack to the flattened end of the rod in such a position that the point lay exactly against the center of the disk. The disk could then be turned up or down, to cover or uncover the point of the rod, as desired. The rod was fitted snugly into a hole in the
Fig. 156. Nut Set in Baseboard. baseboard, and could be raised or lowered to any extent desired, but we had to provide some sort of an arrangement for making it stay where it was put. A small hole was drilled from the edge of the baseboard through to the hole in which the rod was fitted. A square socket was chiseled out around the small hole to receive a nut. The nut was firmly wedged in and held in place by driving in nails along the edges. A bolt or machine screw was threaded through the nut, so that its inner end pressed against the sighting rod. By tightening this screw the rod could be secured at any height desired.

The instrument was mounted on a tripod similar to the one used for our surveying instrument. To this it was attached by means of a bolt, which passed through the center of the baseboard and the tripod head.

The Screen.

The screen, or shutter, of the heliograph was mounted on a separate tripod, so as to prevent shaking the mirror when it was operated. It was made something like a window shutter. We cut out two slats, each 2-1/2 inches wide and 6 inches long. They were made of hardwood 3/8 inch thick.
Fig. 157. Section through Shutter. The upper and lower edges were tapered down to a thickness of 3/16 inch. Light nails were driven into the slats at the ends, and the nail heads were then filed off so that the projecting ends formed trunnions for the slats to turn on. The slats were linked to a connecting rod with double point tacks. A small double point tack was driven into the upper edge of each slat about 1/2 inch from the right hand end. Then through each of these tacks we hooked a second double point tack and drove it into the rod. The tacks on the rod were placed just 2 inches apart. A substantial frame was then made of 3/4-inch stuff 1-1/2 inches wide. The frame was square, with an opening that measured 6 inches each way, into which the slats were fitted. Before nailing the frame together we drilled holes in the side pieces for the trunnions of the slats to turn in. These holes were just 1-3/4 inches apart. After the slats had been set in place, the frame was fastened together and then nailed to a baseboard,
Fig. 158. General View of Screen. which was fastened by a bolt to the tripod. The shutter was operated by a key something like a telegraph key. It was made of a narrow stick of wood hinged at one end to the lower strip of the shutter frame, and a spool sawed in two was fastened to the other end to serve as a handle for the key. A string connected the key with the connecting rod. The slats were kept closed by a spring, which was fastened at one end to the connecting rod and at the other to the top of the frame. At first we used a rubber band for this purpose, but it soon wore out, so we then made a spiral spring out of stiff spring brass wire by wrapping it around a pencil. When the key was pressed down the slats would be turned open, as shown in Fig. 159; but as soon as the key was released the spring would pull them back again.

Focusing the Instrument.