aise many weights; a pile-driver with its automatically
dropped weight, the sound of which never failed to attract
attention,--all these, with other models, occupied a space in Machinery
Hall.

During the morning hours, curtains screened the models; in the afternoon
the youthful exhibitors arrived and took special delight in showing the
working of their designs. The pleasant hours spent there, the praise of
visitors, and the recognition and commendation accorded by the press
will be long remembered by the boys. At the closing of the Fair, the
exhibit was awarded the Medal of Merit.

The illustrations on pages 548 and 550 show the models exhibited. Figure
1 represents an alcoholic furnace, illustrating the expansion of a brass
rod by heat. A cylinder of tin, fifteen inches in height and five in
diameter, is hinged to a base of wood and arranged so as to tilt to the
left. A lever fifteen inches long opens and closes a damper; this lever
(an umbrella rod) is inserted in a pivoted rod of wood two inches long,
supported in a square frame made of an inch strip of tin bent twice at
right angles and soldered to the cylinder.

A brass banner rod, seven inches long, also connects with this rod and,
passing through an inch opening, is supported in the flame of an alcohol
lamp and fastened on the opposite side by a tiny brass knob screwed on
the protruding thread of the rod. A small pulley and weight steadies the
motion of the lever.

The heat of the alcohol flame causes the brass rod to lengthen, and this
in turn moves the lever which opens the damper; and the degree of
expansion is indicated on a paper scale by a straw pointer attached to
the rod of the damper. A coating of copper bronze was given to the
cylinder. This model was made in part by Winfred C. Rhoades.

Figure 2 shows a forge made by William E. Tappae. A hand-bellows is
mounted on a wooden base about ten by twenty-four inches in size, and is
worked by a lever handle supported in a frame twenty-six inches in
height. The bellows consists of two boards connected by flexible leather
tacked to the edges. The upper board is stationary, and an inch central
opening is covered on the inside by a two-inch flap of chamois fastened
at one point, forming a valve.

As the handle is pushed up, the air rushes in, and when pulled down, the
valve closes and the compressed air is forced through the metal nozzle
to the glowing coals. The carved-wood anvil was stained black and the