** Insulating Aluminum Wire [306]

Aluminum wire plunged hot into a cold solution of carbonate of soda becomes coated with a strong layer of oxide which forms an excellent insulator to electricity.

** How to Build an Ice-Yacht [307] Condensed from an article by H. Percy Ashley in Rudder.

The plans and specifications shown in the illustrations are for making a 400-ft. class ice-yacht, having a double cockpit to accommodate four persons.  The weight of the persons in the forward cockpit keeps the boat from rearing when in a stiff breeze.  The forward cockpit can be removed if necessary.  The materials used are:  backbone,

[Illustration:  Ice-Yacht Complete]

white pine; center, clear spruce; sides, white oak caps; runner plank, basswood, butternut or oak; cockpit, oak; runners, chocks, etc., quartered white oak.  All the iron work should be first-grade Swedish iron, with the exception of the runners, which are soft cast iron.

It is not necessary to go into detail with the measurements as they are plainly shown in the sketches.  The backbone is 37-1/2 ft. over all, 12 in. in the center, 5 in. stern, 3-1/2 in. at the nose; width 4-1/2 in.  All wood should be selected from the best grades, well seasoned and free from checks.  In Fig. 1 is shown the complete ice-yacht with general dimensions for the sail and main parts.  Other dimensions are shown in Fig-, 2.  The backbone is capped on the upper and lower edges full length with strips of oak, 4-1/4 in. wide and 5/8 in. thick.  The lengthwise side strips of spruce are 1-1/4 in. thick.  The filling-in pieces placed between the side pieces are of seasoned white pine, leaving the open places as shown in Fig. 2.  The parts are put together with hot glue and brass screws.

The runner plank should be placed

[Illustration:  Details of the Ice-Yacht Parts]

with the heart of the wood up, so as to give the natural curve from the ice so that it will act as a spring.  The plank is 16 in. wide in the center, 14 in. at the ends; 4-1/8 in. thick at the center and 2-3/4 in. at the ends.

Details of the runners are shown in Figs. 3, 4, 5, 6, 7, 8 and 9.  The cast iron shoes are filed and finished with emery paper, making the angle on the cutting edge 45 deg. on both sides.  The runners are 7-1/4 in. wide over all and 2-1/8 in. thick.  The soft iron casting is 2-1/4 in. deep.  The shoes are fastened by 5/8-in. machine bolts.  These are shown in Figs. 3 and 9.  The rudder is 2-3/4 in. thick, 5 in. deep, including wood and iron, and 3 ft. long.  The cast iron shoe is 1-7/8 in. deep and fastened on with four 1/2-in. machine bolts.  A brass plate, 1/4 in. thick, 2 in. wide and 7 in. long, is inserted on each side of the runners as shown in Fig. 9.  Three holes are drilled through for a 3/4-in. riding bolt that can be shifted as desired for rough or smooth ice.  The runner chocks and guides are 1-7/8 in. thick and 4-1/2 in. deep.  They are set in the runner plank 1/4 in. and fastened with glue and 1/2-in. lag screws.  These are shown in Figs. 6 and 7.