54 T. A, Edison— Use of the Tasimeter. 
pin, thus increasing the resistance of the shunt perhaps to one- 
fiftieth of anohm. The spot of light was generally deflected 
nearly off of the scale. The light was again brought to zero 
by varying the resistance of the tasimeter, and another one-half 
inch of wire included in the shunt, another deflection and 
another balance’ was obtained by the tasimeter. Thus s by 
gradually increasing the delicacy id the ,galvanometer ate in- 
creasing the resistance of the shunt and ba alancing at eve 
increase, the whole of the ourieat was allowed to ae throug : 
the galvanometer and the shunt taken off. this point — 
was reached the damping magnet or director was in close prox: 
imity to the case of the galvanometer. To increase its delicacy | 
to the fullest a it became necessary to raise the director to — 
the top of the rod. This was done by raising it cautiously a_ 
quarter of an inde at a time, bringing the spot of light to zero ~ 
each time by the tasimeter. | 
In order to form some idea of the delicacy of the apparatus — 
when thus eee a SE experiment was made on the | 
evening of the 27th, with the star Arcturus. The tasimeter | 
poe sdabted to the Ean the image of the star was | 
ought on the vulcanized rubber. The spot of light from the — 
balesnanasesk moved to the side of beat. After some minor — 
adjustments, five uniform and _ successive deflections were 
obtained with the instrument, as the light of the star was allowed — 
to fall on the vulcanite to prod uce the deflection, or was screened — 
off to allow of a return to z 
It was in this condition Shen the eclipse occurred. The tasi 
meter was placed in a double tin case, with water at the tem 
peratone of the air Siena oe case. This case was secured 
towards heat, its velocity accelerating as it approached the e 
The time required for the light to leave the scale was from 
four to five seco 
I interposed he screen and endeavored to bring the light 
back to zero, but I was unsuccessful. Had I known that 
corona. 
Respectfully peu THomas A. EDISON. 
Menlo ie N. J., August 15, 1 
