18 MEASUREMENT OF HIGH TEMPERATURES. 
(6) Phenomena of elasticity and viscosity; considered, as before, with especial refer- 
ence to their dependence on temperature and pressure, 
(c) Phenomena of heat conductivity under analogous circumstances. 
The article then proceeds to select the relation between me 1 ting point 
and pressure, as a problem the experimental difficulties of which are 
perhaps least formidable ; as a problem, moreover, which for thermo- 
dynamic reasons may judiciously be decided upon as a point of depart- 
ure. It develops certain general methods by aid of which increments 
of high melting point, however relatively small, are measurable even 
under conditions of very high pressure. It concludes by signaling the 
importance of special and preliminary researches on the measurement of 
high temperatures and of high pressures, with a view to the selection of 
such/details of method as will best subserve the purposes in question. 
Throughout the present research the points here mentioned have 
been carefully kept in mind. It is my judgment that few important 
steps in dynamical geology will be made until the methods for the 
accurate measurement of high temperatures and of high pressures have 
not only been perfected but rendered easily available. On the basis of 
this conviction the present memoir on high temperatures has been 
prepared; and though the experiments on temperatures may seem to 
have been pushed to some detail, I can not regard them either as pro- 
fuse or as superfluously ambitious. Indeed, if the investigation be of 
any fullness, it is almost essential that the observer master the com- 
ponent parts of his research separately; and not until he has satis- 
factorily done this can he apply them conjointly. In work like the 
present, moreover, the value of the data can scarcely be determined 
except by the degree of uniformity of great numbers of results. 
In June, 1882, Dr. Strouhal resigned his charge to take a professor 
ship at the University of Prague. At my request Dr. William Hallock 
was appointed to fill the vacancy, and, being at the time associated with 
Dr. Strouhal in certain duties abroad, he was easily able to complete 
the work which the latter had been compelled to leave unfinished. Dr. 
Strouhal made the purchases of all the instruments we desired to buy 
in Germany, while Dr. Hallock, following my instructions, proceeded to 
purchase such apparatus as could best be obtained in France. 
About this time the rooms which had been placed at my disposal by 
the American Museum at New York became temporarily unavailable. 
Moreover, as Dr. Hallock had joined me, more room than the museum 
afforded was desirable. After due deliberation we determined to rent 
a house in New Haven, Conn., and thither the laboratory was removed 
in November, 1882. Our reasons for selecting New Haven were, briefly, 
that a satisfactory house for practical laboratory purposes could be ob- 
tained more reasonably there than elsewhere; and that the city offered 
excellent library and other facilities for scientific work, such as can be 
met with only in the immediate vicinity of a large university. We have 
abundant cause to thank the gentlemen in charge of the scientific de- 
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