Page:Popular Science Monthly Volume 92.djvu/786

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��Popular Science Monthly

��pole plates and into the mast plates, step a couple of curtain poles. Keeping the center of the mast plates on the center line of canoe, move them forward and backward until both masts have a pleas- ing and identical rake, when the position of the mast plates and their screw holes may be marked on the floor plates.

���The shape of the blanche cleat and the clutch cleat for mizzen sheet both in brass

After drilling for these, countersink on the under side of floor plates. This permits the removal of mast plates without taking up floor plates as the nuts and washers will be on upper side.

The floor grating should be cut away as in Fig. 12 if it interferes with the in- stallation of floor plates. Dotted lines under the floor plates indicate portions of two grating strips in way of floor plate. Broken lines along ends of plate show how these, when sawed away may be utilized as cross braces to keep the ends of short- ened strips in place.

When all steps are permanently fast- ened, re-step the curtain poles. Near lower end of foreward one, and just high enough to keep from marring the deck, tie a brass pulley block with a ^^-in. sheave. Tie another near the mast head so that you can hoist the mainsail as shown in Fig. 13. The governing conditions are that the forward end of boom must not foul forward deck and that the after end of boom must clear head of passenger seated beneath it. The mizzen should be at same height above floor at jaw as the mainsail, boom should have same lift and should clear after deck. Manipulate both sails until these conditions are met. Then mark on the yards the position of halliards and on the masts the positions of upper blocks, and mast plates. These dimensions give you data for your mast specifications. From butt of curtain poles to 6 in. above upper blocks will be length of mast. From floor to flag pole plates they should be cylindrical and 1 ^.j in. in diameter. From flag pole plates to

��mast head they must taper to 13^ in. diameter. Instead of upper block on mizzen mast, a sheave set in a mortise will be an improvement. Let sheave be 1 }/$ in. diameter and ^/g in. thick. Mortise to take this should be 2 in. long and 3^ in. wide and its center one inch above place already marked for block.

When masts are finished, set the halliard blocks with brass screw-eyes which have been opened and closed over the eyes on blocks. Put around each mast, 1 in. above and below each jaw, a leather collar 14 in. thick and 1 in. wide, attached with copper tacks. Soak in water to make pliable before attaching and shellac after they have dried. These collars prevent sails from hoisting too high or booms falling on decks when low- ered. To keep mizzen out of the water when lowered, run an endless line through a screw-eye on masthead and through another one on boom as shown in Fig. 13. Use }4 in- clothes line for halliards and sheets and let main sheet run through a ring on boom and fasten with a snap to a ring lashed to center of thwart. When close hauled, this gives a double purchase and when cast off in running ahead of wind doubles the length of sheet. The mizzen sheet passes through a screw-eye on after deck, as shown in Fig. 13, to a clutch cleat, Fig. 14, placed within reach of the skipper's left hand. To belay halliards, two blanche cleats. Fig. 15, are attached to right hand in-wale within reach of the right hand. That for the mainsail has the hook set aft, and that for the mizzen has the hook forward. {To be continued)

��Freezing a Glass Tumbler to a Block of Wood

SELECT a small, planed block of hard wood and place upon it a few drops of water and then a glass tumbler having a smooth bottom. Pour about 1 in. of water into the tumbler and add powdered ammonium nitrate, stirring the mixture constantly. As the ammonium nitrate goes into solution, it absorbs heat, pro- ducing a low temperature which quickly freezes the tumbler fast to the block, so that the latter will not fall when the tumbler is lifted from the table. Frost also gathers on the outside of the tumbler.

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