;312 KANSAS CITY REV JEW OF SCIENCE. 



ence to the Coming Transit of Venus," which was received with enthusiastic ap- 

 plause. He divided the methods for finding the sun's parallax into three classes, 

 the trigonometrical, the gravitational, and the third, the name of which he coined 

 for the occasion, the pho-tachymetrical. The latter is the best, and consists in a 

 process by means of the use of the measurements of the velocity of light. This 

 method, the most modern, was fully explained and illustrated by blackboard 

 drawings. 



Professor T. C. Mendenhall opened the afternoon session by reading an elab- 

 orate and quite interesting paper "On the Wave-lengths of the Principal Lines 

 of the Solar Spectrum." It consisted of a brief discussion of the processes and 

 instruments made use of in the measurement of wave-lengths, of certain imper- 

 fections, in the defraction, grating 'and causes to which they are due, and the 

 numerical results of the investigation. He showed that the inequalities observed 

 in solar spectra were due to the variations in the plane of polarization, and con- 

 cluded with a prophecy that in the future the use of the wave-length of light as 

 the standard of linear measure would be as universal as the use of water as the 

 standard of density. 



Samuel Marsden, of St. Louis, read a description of his experiments to de- 

 termine the comparative strength of globes and cylinders of the same diameter 

 and thickness. He exhibited some lead globes and cylinders four inches in in- 

 ternal diameter and one-fourth of an inch in thickness, which he had used in his 

 experiments with a hydraulic testing machine. The theoretical strength of the 

 cylinder is proportional to the diameter and tensile strength of its sides. Calcu- 

 lating this, and comparing it with the results of the actual strength, as determined 

 by his experiments, it was found that in but one case out of eight was the result 

 identical. This he ascribed, not to the imperfection of his experiments, but to 

 the failure of the rule. 



Mr. T. Sterry Hunt then explained his peculiar views upon the nature of 

 interstellar ether by an address on " Historic Notes on Cosmic Physiology." 



" The White Pine : Its Origin and Natural History ; Statistics of Its Industry 

 in Michigan; The Coming Substitute for Lumber," by William Hosea Ballou, of 

 Evanston, 111. This paper possesses much general and commercial, as well as 

 scientific value. The author showed that at the present rate of demand the white 

 pine supply will be exhausted in about seven years. 



Science will doubtless devise other material's as a substitute. Indeed, I have 

 Deen shown a material manufactured in Chicago in the shape of a board one inch 

 thick, made from wheat straw, which can be colored to represent any lumber 

 now known, so accurately as to deceive the eye. The inventor manufactures 

 two thousand square feet from a ton of straw. It is more durable and much 

 cheaper than lumber. As a parallel to the use of paper wheels, Mr. Pullman is 

 now finishing off three palace cars in this material. The limit of its manufacture 

 will depend only on the production of wheat straw. 



The proceedings of Section C, Chemistry, were opened by a discussion of 

 the paper presented yesterday by Mr. H. C. Hovey, on " Coal Dust as an Ele- 



