18 THE AMERICAN MONTHLY [January, 



Novembej' 7, i88g. — At the residence of Mr. W. W. Underhill, 

 Montclair. The paper for the evening was by Professor Julien, who 

 instructed the members in the art of making rock sections. The prepa- 

 ration of these sections by grinding was very fully explained, and a 

 large number of slides exhibited on the screen. Their internal structure 

 was very beautifully exhibited by means of tlie polariscope, and the 

 component minerals disclosed. 



The list included granite, pyroxene, agate, tourmaline, gneiss, mico- 

 schist, demyte, olivene serpentine, diorite, norite (from the Adiron- 

 dacks), pudding stone from England, sandstone from Dorchester, and 

 many building stones. 



The value of the microscope and polariscope in determining the quali- 

 ties of a building stone were made very evident, as the internal structure 

 of the rocks could be so easily observed, and also the cementing mate- 

 rial which united the different minerals. Altogether the lecture was 

 very enjoyable and instructive. 



o 



Iron City Microscopical Society. 



Tiiesdav evenings Dec. JO., i88g. — The exercises were opened with 

 a talk by Rev. W. J. Holland, on the " Best Methods of Mounting 

 Insects." The modes of collecting, preparing, and stretching were 

 fully discussed and explained, the more intricate points being illustrated 

 by drawings. Regarding the best method of collecting moths, the 

 lecturer described the mode used by himself. He made a mixture of 

 common brown sugar and stale beer, applying it to the forest trees on 

 the side towards the moon, with a common whitewash brush. Then 

 approaching the tree cautiously, using a dark lantern, he was enabled 

 to pick oft' the moth wanted. In this way he collected over 600 speci- 

 mens in one night in Southern Indiana. The best mode of killing the 

 LejDidoptera is with potassium cyanide. To prepare this important part 

 of a collector's outfit, procure a wide-mouthed bottle (Scherin's chloral 

 hydrate bottles are best), drop in two or three pieces of potassium 

 cyanide about the size of hickory nuts. Then cover the cyanide loosely 

 with a few layers of paper. The common method is to imbed the 

 cyanide in plaster of paris, butinMr. Holland's experience the method 

 used is superior to the other. 



Mr. C. C. Mellor then entertained the large audience present with a 

 lantern exhibition, using a Mcintosh lantern with a 2" objective. 

 The objects thrown on the screen were clearly and sharply defined. 

 The usual exhibition of slides followed : W. J. Prentice, exhibiting 

 section of Canada pine ; J. H. McRoberts, a section of red oak ; J. G. 

 Ogden, section of lung of kitten, injected ; J. A. Moore, pollen of 

 corn. [Reported by Gordon Ogden.] 



NOTICES OF BOOKS. 



EIei?ientary Mathematical Tables. By A. Macfarlane, LL. D. 8°, 



cloth, 113 pp. Ginn & Co., Boston. Price 85 cents. 



This collection of tables contains logarithms, antilogarithms, addition 



and subtraction logarithms, logarithmic sines and cosines, logarithmic 



tangents and cotangents, natural sines and cosines, natural tangents and 



