722 KANSAS CITY REVIEW OF SCIENCE. 
ness portion of the city. The ball which passes over the staff, is simply a wire 
skeleton covered with canvas and painted black, and is about three feet in diame- 
ter. It was loaded on the inside with lead until it was found to drop instantly 
and without loss of time. It has a drop of about twenty-five feet and is slowed 
up as it reaches the bottom, and is received upon a set of tall springs surmounted 
by a stout cushion. 
The apparatus used in dropping it is shown in the accompanying cut. 
It is the arrangement of Mr. William F. Gardner, the skillful instrument 
maker at the Naval Observatory, who probably has had a wider experience in the 
construction of such apparatus than any one else in this country. 
The machinery is simple and easily understood from the figure and answers 
every purpose. Itis mounted in a box about two feet high and fifteen inches 
wide, which is firmly screwed to a table beneath. The cut shows it as it stands 
SYA BRsepen 
ili _f 
| : 
agi = which is drawn 
co 
TT up to the top of 
the staff 5 min- 
utes beforenoon, 
The ropes (it) 
which hold the 
ball in place are 
shown in the 
figure passing 
through a ring 
(G). The bolt 
which holds this 
ring 1s a contin- 
uation of the per- 
pendicularpiece 
(L). This is be- 
ing constantly 
Mh pressed back to- 
| HAA ward the right 
AN by a strong 
spring conceals 
ed under (H), and is only kept from flying back by the small arm (B), which 
fits into a notch on the end of (E). (A) in turn is kept from flying out to the left 
by the armature (R) of the magnet (A). As soon now as the circuit is closed at ’ 
the Observatory at noon, this armature is instantly pulled down, the piece (B) flies 
out to the left, the ring is released and the ball drops. This has been found to: 
work easily and without loss of time and can scarcely get out of order. The en- 
tire cost of mounting the ball and machinery was only about $120, and with this 
