[Illustration:  Table Lifting Device]

rest the hands upon it and at the same time press the needle points in the arm pieces into the wood of the table, which will be sufficient to hold it, says a correspondent of the Sphinx.  Then walk down among the audience.

** How to Make a Paddle Boat [100]

A rowboat has several disadvantages.  The operation of the oars is both tiresome and uninteresting, and the oarsman is obliged to travel, backward.

[Illustration:  Paddle Boat]

By replacing the oars with paddles, as shown in the illustration, the operator can see where he is going and enjoy the exercise much better than with oars.  He can easily steer the boat with his feet, by means of a pivoted stick in the bottom of the boat, connected by cords to the rudder.

At the blacksmith shop have a 5/8-in. shaft made, as shown at A, Fig. 2.  It will be necessary to furnish a sketch giving all the dimensions of the shaft, which should be designed to suit the dimensions of the boat, taking care that sufficient clearance is allowed, so that the cranks in revolving will not strike the operator’s knees.  If desired, split-wood handles may be placed on the cranks, to prevent them from rubbing the hands.

The bearings, B, may be made of hardwood, but preferably of iron pipe filled with melted babbitt.  If babbitt is used, either thoroughly smoke or chalk the shaft or wrap paper around it to prevent the babbitt sticking.  The pieces of pipe may be then fastened to the boat by means of small pipe straps, such as may be obtained at any plumber’s at a very small cost.

The hubs, C, should be made of wood, drilled to fit the shaft and mortised out to hold the paddles, D. The covers, E, may be constructed of thin wood or galvanized iron and should be braced by triangular boards, as shown in Fig. 1.  If galvanized iron is used, it should be exposed to the weather two or three months before painting, or the paint will come off, spoiling its appearance.

[Illustration:  Detail of Paddle Boat]

** Peculiar Properties of Ice [100]

Of all the boys who make snowballs probably few know what occurs during the process.  Under ordinary conditions water turns to ice when the temperature falls to 32 degrees, but when in motion, or under pressure, much lower temperatures are required to make it a solid.  In the same way, ice which is somewhat below the freezing point can be made liquid by applying pressure, and will remain liquid until the pressure is removed, when it will again return to its original state.  Snow, being simply finely divided ice, becomes liquid in places when compressed by the hands, and when the pressure is removed the liquid portions solidify and unite all the particles in one mass.  In extremely cold weather it is almost impossible to make a snowball, because a greater amount of pressure is then required to make the snow liquid.

This process of melting and freezing under different pressures and a constant temperature is well illustrated by the experiment shown in Figs. 1, 2 and 3.  A block of ice, A, Fig. 1, is