OF ARTS AND SCIENCES. 525 



the reduction and publication of the observations are wholly inadequate ; 

 while some of the largest telescopes in the country, representing a plant 

 costing hundreds of thousands of dollars, are nearly idle and therefore 

 useless. Observations of the greatest value can be obtained with these 

 instruments at small expense, and it is hoped that the beginning now 

 made will justify its permanent continuance on a large scale. The 

 problem undertaken is the determination of the light of faint stars, se- 

 lected as standards. These will furnish points of reference to which 

 other photometric measures may be referred. Five photometers have 

 been constructed in which, by interposing a photographic wedge of shade 

 glass, an artificial star is reduced in brightness until it appears equal to 

 a real star, as seen in a large telescope. Thirty-six regions have been 

 selected in different parts of the sky, in each of which a series of stand- 

 ards is to be measured. Five stars of about the twelfth magnitude, 

 five of the fifteenth, five of the sixteenth, and five of the seventeenth 

 are to be chosen in each of these regions. The faintest stars will be 

 selected and measured with the Yerkes 40-inch and Lick 36-inch tele- 

 scopes. Those of the sixteenth magnitude will be measured with the 

 26-inch telescope of the University of Virginia and perhaps the Prince- 

 ton 23-inch telescope. The stars of the fifteenth magnitude will be 

 measured with the 15-inch Harvard telescope. All of these stars will 

 be compared with the stars of the twelfth magnitude, when absolute 

 magnitudes will be determined with the 12-inch Harvard meridian pho- 

 tometer. Their relative brightness will also be determined more accu- 

 rately with the Harvard 15-inch telescope. After the work is fairly 

 started it is believed that it can be reduced to a simple routine, by which 

 great results may be attained with a moderate expenditure. By the 

 time this report is presented, it is expected that observations with the 

 Yerkes, Lick, University of Virginia, and Harvard telescopes will be 

 in progress." 



PROFESSOR B. O. PEIRCE. 



Grant of December 2, 1892, $200, and April 26, 1895, in aid of an 

 investigation on the propagation of heat in certain solid bodies. 



Professor Peirce writes that he " published last summer in the Pro- 

 ceedings of the Academy a short paper on the 'Thermal Conductivity of 

 Vulcanite,' giving therein the results of a long series of experiments. 

 This paper in a somewhat extended form appeared in the Philosophical 



Magazine." 



A paper on the specific heats of different marbles is also ready for 



publication. 



