150 BOTANICAL GAZETTE. [ July, 
The interrupted movement may be brought about by af 
ing a strip, ¢, bearing at regular intervals round wire nails, 
attached to the lower portion of the carriage. nae 
One of these nails is held for a certain time by the hoo 
h (fig. 5), which is attached to the strip 2 (figs. = i 
which moves about the pivot g& (fig. 1). Finally, w “ 2 
elevated, 4’, which is attached to a similar and paralle “ 
and moves with f about g, catches the next succeeding Tk 
and holds it a regular period, before allowing it to reach /. 
A short horizontal line is thus drawn by the style at # 
fig. 2 
3 i 
The elevating and depressing of the escapement at fe 
brought about by attaching the works of one of the § bid 
nickel-plated clocks, which will run when held in any : 
tion, to a board, & (figs. 2 and 3). In place of the hee 
hand” there is attached a crank which will play throug xii 
slot 7 (fig. 5). As the post turns the crank toward ae 
o'clock 4 will be elevated, and at VI o'clock, thirty rail 
later, 4’ will be depressed to its greatest, one nail thus s iy 
by every half hour. The escapement hooks may be easily 
cut out of two pieces of tin. an 
If the arm does not swing parallel with the smoke 
face, change the screws at x (fig. 3). 0, 8s 
One recommendation the apparatus has is its nea 
Siveness, costing, with the clock, if one is his own ate oe a 
not more than three dollars. Another is the ease with 7 ‘he 
the records for several half hours may be compared, - i 
little labor necessary to prepare permanent recor - me 
simply placing the glass ona piece of ‘** blue print” pap® — 
and exposing to sunlight. 
A registering anxanometer. 
CHARLES R. BARNES. = | 
(WITH PLATE vutI.) on 
: ; ion [0 
In January last my class in physiology had one sae 
study the rate of growth of seedlings under various cent 
tions. I needed an instrument to keep a continuous Te 
of their growth, and Ger ‘c shop 
one. ith the help of the students in the mechanic : 
arranged and constructed the instrument here describe es no 
1S Comparatively simple and inexpensive, and requil' | 
