1887. | BOTANICAL GAZETTE, 151 
work which can not be done by a turner and a machinist, at 
slight cost. ! 
fe, plate VIII, is a cylinder of pattern pine, twelve inches 
long and three in diameter; centered in its ends are two 
pieces of brass rod about three-eighths of an inch in diameter, 
the lower and longer of which, 4, is coned on its free end and 
Carries about its middlea drum, f. Thisisa silk-spool bored 
out alittle. The lower axle of the cylinder rests upon a piece 
of glass hollowed to receive its point, and the upper passes 
through a small plate of brass, 2, (figs. A and ZY), bored to 
fit it smoothly and screwed to a light frame of wood, 3; X 2. 
he upper or cross-piece is seen at J, with ends dovetailed 
to fit the side pieces. This top piece can be lifted out so as 
to allow the removal of the cylinder. 
Around the drum, /, passes a cord, over the pulley, 7, to 
the weight, m. The pulley is made of a section of a spool 
With a groove filed around it, revolving ona glass rod. By 
the fall of the weight, m, the cylinder would rotate continu- 
ously were it not for twelve equidistant pins, 0 0, whic 
gage with the armature, #, of an electro-magnet, e. The 
Pins are wire-nails, driven in and cut off, and in a second 
instrument were placed radially around the lower end of the 
cylinder so as to use a straight armature. 
The electro-magnet is one of the simplest form and can 
be had of dealers in electrical apparatus. I first adapted a 
relay instrument to this use, but afterwards wound a magnet 
with number twenty-four silk-covered wire and made it a 
permanent part of the apparatus. The magnet is connected, 
4s shown in the figure, with a battery, W, through the clock, 
2, so arranged by tying the striking wheel as to strike but 
nce each hour. One wire from the battery (the LeClanché 
cell used for door-bells) is soldered to the hammer arm, vz. 
Its continuation is soldered to a piece of watch-spring, @, so 
fixed that the hammer, z, as it draws back to strike will come 
im Contact with it. 
turner who makes the cylinder. It is double, having a large 
Part, 4, and small part, a. This wheel must be so balanced 
that it will stop at any point indifferently. If not turned ac- 
Curately counterpoises of flat bits of metal can be attached 
