1896 ] BRIEFER ARTICLES : 261 
on a wooden base provided with three leveling screws and will run 
four days without winding. It is made especially for light objects 
although I have carried fourteen pounds on it in a horizontal position 
fora number of hours. The apparatus could be constructed, I sup- 
pose, for about $15. 
Spring dynamometer (f/. X, jigs. 7 and 2).—This apparatus was 
devised for the purpose of measuring the power of growth induced by 
geotropism in grass nodes. It consists of a watch spring (a) having 
attached to its end a straw (4) which amplifies the movement on the 
graduated scale of the arc (c). The straw is held securely by means of 
a spiral wire (¢) soldered to the underside of the spring, allowing 
the straw to be removed at leisure. Directly above this straw is a wire 
loop for attaching a thread, the other end of which is fastened to the 
Stass culm at a distance from the node of 4%. The grass culm has 
its lower end inserted in a bottle containing water provided with a 
perforated cork through which is placed a glass tube tightly fitting the 
culm, thus holding it securely. The bottle is supported by an Arthur 
clamp and is mounted on a vertical rod which can be adjusted to any 
desired angle by a unique joint (7) made by the O. C. White Com- 
26 Worcester, Mass. By lengthening or shortening the spring the 
a can be readily varied. In the illustration the whole watch 
‘pring is shown, but of course only a short piece is necessary. 
" scuaneaaeg for measuring and recording root-growth (//. x, fi: Do 
of pa, i ae in my experiments to record the hourly increments 
Sself- cc ae . e length of a large number of roots I was obliged to devise 
self-re is ung alae for this purpose. So far as I am aware no 
he ona appliance has been employed in the growth of roots. 
icscinie a general use consists in direct readings with a horizontal 
hie se one who has employed this method must be aware 
account of ay tedious, and, moreover, that it is not cme ” 
lable to civ si os peat the root, which under high magnification 1s 
tutes ee ay to serious errors in the readings. he root consti- 
fore that c.. most delicate organs of a pliant, and it is clear ong 
kind, It ee os apparatus we use must be of the most. sensitive 
amount of % . able to keep the root straight, yet allowing a eee 
injure the and it must be constructed out of material which will no 
Possess the lea: . a8 the appar _ which multiplies the growth must 
i des i resistance possible. 
cribing this apparatus it will not be necessary to go into the 
