702 
glance one can observe which cells are in use. 
Fig. 6 shows the electrical connections from 
one of these distributing boards to the cells 
and outlets on the working tables. The 
levers themselves are too narrow at their 
outer ends to reach across from one block 
to another, to prevent short circuiting the 
cells, so they are provided with fiber exten- 
tensions on each side to prevent their fall- 
ing between the blocks, and also to prevent 
their making contact with each other. The 
switchboard on the west wall is exactly 
similar to the one just described, it contain- 
ing the circles G, H, I, K, L, and M, while 
the third one, which controls the four out- 
lets on the center table, is but twenty-four 
HANH 
Wyn SOU Uo ee 
SCIENCE. 
[N. S. Von. XIII]. No. 331. 
charge rate of the cells exceeds the greatest 
estimated current needed by one operator. 
All brass parts on the back of the board, 
as well as the bared ends of the wires, are 
thoroughly coated with P. and B. paint, 
while the brass parts on the front are heavily 
lacquered to prevent corrosion. The surface 
of the contact blocks can easily be cleaned 
with fine sandpaper. 
“The measuring instruments, after some 
deliberation, were chosen of the switch- 
board type. While this necessitated pro- 
curing at least one-third more instruments, 
yet the initial cost was considerably lower 
than if portable instruments had been pro- 
vided, and experience with portable instru- 
Fria. 6. Connections to Working Table. 
inches square, but has twenty-six contact 
blocks in each circle. They are numbered 
0, 24, 25, 26, and so on to 48. Between 
the two blocks numbered 0 and 24 are con- 
nected the cells of the group on the east 
side of the room ; between the blocks 24 and 
25 is connected cell No. 1 of the west side 
of the room, while cell No. 2 is connected 
between blocks numbered 25 and 26. This 
arrangement connects the two groups of 
cells in series, and permits the use of from 
one to forty-eight cells at the center table 
when necessity requires. It will, perhaps, 
have been noticed that there is no provision 
made for connecting cells in parallel, and 
this is not necessary, as the maximum dis- 
ments leads me to believe that a greater 
accuracy will be attained with switchboard 
instruments of a good form, if not immedi- 
ately, yet surely after the first six months 
of use. 
“Hach outlet is provided with a fused 
switch, a voltmeter, two ammeters, a rheo- 
stat and a terminal board. They are con- 
nected as shown in Fig. 6. The positive 
lead after passing through the variable re- 
sistance runs directly to the positive bind- 
ing post. The wire coming from the nega- 
tive binding post runs to the low reading 
ammeter and thence to the negative side of 
the switch, while the negative post marked 
25 is connected to the same switch terminal, 
