OF ARTS AND SCIENCES : MAY 12, 1868. 483 



over the distorted forms now in use. Horizontal distances being pro- 

 portional to the change in the index of refraction, the latter could be 

 determined at once for any line, by a scale of equal parts. Its extent 

 would be much greater than that of the visible spectrum, and we could 

 determine the index of refraction of rays of too short wave-length to be 

 measured readily by the common methods. It would be a normal 

 spectrum for any given material, being independent of the form and 

 position of the prism. And (especially if the interference bands were 

 produced in it) it would afford, from its extent, great advantages for the 

 study of the laws of the dispersion of light by different substances. 



Five hundred and ninety-fourth Meeting. 



May 12, 1868. — Monthly Meeting. 



The President in the chair. 



The Corresponding Secretary read letters relative to ex- 

 changes ; also a letter from Professor De La Rive in acknowl- 

 edgment of his election into the Academy as a Foreign Hon- 

 orary Member. 



Mr. C. M. Warren presented by title a memoir on " Vola- 

 tile Hydrocarbons in Pennsylvania Petroleum." 



DONATIONS TO THE LIBRARY, 



FROM JUNE 2, 1865, to JUNE 30, 1866. 



State of Massachusetts. 



Report to His Excellency the Governor and the Honorable Coun- 

 cil, of the Commissioners appointed under the Resolve of May 3, 

 1865, " concerning the Obstructions to the Passage of Fish in the 

 Connecticut and Merrimack Rivers." 8vo pamph. Boston. 1866. 

 Massachusetts Historical Society. 



Proceedings. 1864-1865. 8vo. Boston. 1866. 

 Massachusetts Institute of Technology. 



First Annual Catalogue of the Officers and Students, and the Pro- 

 gramme of the Course of Instruction, of the School of the Massachu- 

 setts Institute of Technology. 1865-66. 8vo pamph. Boston. 

 1865. 



