678 KANSAS CITY REVIEW OF SCIENCE. 
Adams in the first part of his article discusses the subject in general, and we will 
give the remainder in his own words.—R. W.B. | 
My researches now remzined 7” sta/u guo for some time, when one day, in 
the course of conversation with Dr. J. Harry Thompson, of Washington, D. C., 
he suggested the utilization of the newly discovered property of carbon to vary 
its conductivity under different degrees of pressure. 
I immediately availed myself of this suggestion, developing the instrument 
as now perfected and illustrated in figs. 4and 5. This is the thermometer proper 
Fi to.5 “Lp 7esolefilarsl igc, 
HH- Handles. 
or responding portion of the instrument, and consists of a spiral spring made of 
two /amelle of brass and steel respectively, soldered together, the brass occupy- 
ing the outer side. Of course this spring expands uniformly with equal incre- 
ments of heat, and the brass, the most expansible of the two metals, will, upon 
a rise of temperature, give the platinum knob (a), attached to the free end of the 
spring, aconcentric twist. In this way we produce a varying pressure upon the 
contents of the vulcanite tube (T), against which the platinum knob (a) impinges. 
The other end of the substance contained in the hard-rubber tube (T) has 
for its abutment the platinum knob (b) attached to the hard-rubber bracket (C). 
The whole, as seen in fig. 4, is inclosed in a perforated German:silver case, with 
rounded edges, and having an external diameter of but 114 inches. . 
The binding-post (A), fig. 4, is in electrical communication with the platinum 
knob (a), and the binding-post (B) is in electrical communication with the platinum 
knob (b). When the apparatus is introduced into an electric circuit, by attaching 
the two poles to the two binding-posts, the current enters through one and 
emerges at the other, passing in its course through the substance in the vulcanite 
tube (T). The two little handles (H) (H) are intended as a means of securing 
