ACADEMY OF NATURAL SCIENCES. 41 



microscopes, an air-pump, a mineralogical apparatus, an elec- 

 trical machine, an inflammable air lamp, and a five feet achro- 

 matic telescope, with an aperture of three and a half inches ; the 

 last was presented in 1841 ; to the late Dr. Troost, for Wollas- 

 ton's reflecting goniometer ; to the late ingenious Isaiah Lukens 

 for a most excellent clock, manufactured by himself, and pre- 

 sented in the year 1818. A club of members, in 1843, presented 

 a copper apparatus, or oven, for disinfecting zoological speci- 

 mens. 



In July, 1847, Mr. Henry Seybert deposited, for the use of 

 members of the Institution, a collection of chemical apparatus, 

 consisting of 1,500 pieces, in glass, earthen-ware and fire-clay, 

 porcelain, agate, platina, and other metals, with a 'variety of 

 scales and weights. 



In 1851, Prof. J. K. Mitchell deposited, for the use of the 

 members, a microscope of the manufacture of Oberhaiiser ; and 

 Mr. John Price Wetherill deposited one of the manufacture of 

 Pritchard. 



18. LIBRARY. 



The library commenced in April, 1812, with a few volumes 

 given by Mr. John Speakman and Dr. Mann. Among the early 

 patrons of the library, Mr. William Maclure, R. E. Griffith, and 

 Zaccheus Collins were prominent. The donations of Mr. Ma- 

 clure alone, up to the time of his death in 1840, amount to 5,232 

 volumes. Lists of the names of the donors to the library are 

 appended to each half of several volumes of the Journal of the 

 Academy ; they are too numerous to be cited here. In the year 

 1841, the library contained 7,000 volumes, since which date the 

 number has been nearly doubled. 



Very few volumes have been purchased or received from public 

 sources ; almost all have been gifts from individuals or societies 

 devoted to the cultivation and diffusion of knowledge. Some are 

 received in exchange for the publications of the Academy. The 

 donors are very numerous. Those who have presented the 

 largest number of volumes since the year 1840, are Dr. T. B. 

 Wilson, Mr. Edward Wilson, and Dr. R. E. Griffith. 



A manuscript catalogue of the library was prepared by Dr. 



