Mathematicians will do well to observe that a reasonable acquaintance — Carl Barus

"I develop a method for the direct and expeditious comparison of the thermo-couple with the air thermometer. A comparison of the data... gives me a criterion of the accuracy with which the data in the region of high temperature are known. This indirect method... is not apparently as rigorous as their direct evaluation by means of the air thermometer; but the indirect method requires much smaller quantities of substance and may be conveniently extended to much higher temperatures. Taking all liabilities to error into consideration, its inferior accuracy is only apparent."

"The boon of an appropriate lemma is ideal generosity, and not even a mathematician can scorn its almost mathematical elegance."

"When the history of the progress of physics in the United States during the late nineteenth and early twentieth century is written, the name of Carl Barus will occupy an important place."

"[F]ew important steps in dynamical geology will be made until the methods for the accurate measurement of high temperatures and 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... [I]f the investigation be of any fullness, it is almost essential that the observer master the component parts of his research separately; and not until he has satisfactorily done this can he apply them conjointly."

"[T]he author, whose work on nuclei is well known, describes a number of investigations carried out with his fog-chamber apparatus. The apparatus having been sufficiently improved, it was used for various experiments, including the growth of persistent nuclei, the production of water nuclei by evaporation, the results obtained when X-rays are allowed to strike the fog-chamber from different distances, the effect due to radium, &c. Other problems dealt with in the book are the distribution of colloidal nuclei and of ions in media other than air-water, the simultaneous variation of the nucleation and the ionization of the atmosphere of Providence, and the variations of the colloidal nucleation of dust-free air in course of time."

"Among recent contributions we may refer in particular to Professor A. G. Greenhills noteworthy papers... when one remembers that these complex curves reach only especially simple cases of motion, one may get some notion of the difficulty of the problem involved."