PKOCEEDINGS OF SOCIETIES. 39 



there was too much dispersion, the bands were thinned out so much 

 that it could not be seen where they ended. So if absorption bands 

 were over magnified, failure would again be the result. For absorption 

 bands enough dispersion was wanted to render them easily separable. 

 There should not be more dispersion, as it rendered the band difficult 

 to be measured. With respect to the size of objects, he had shown 

 about ^rd or ith of the human blood globule with a 20th objective, 

 and the Sorby- Browning spectroscope, and had brought out the cha- 

 racteristic bands. The blood globule as to size was about the 4000th 

 of an inch, and a ^ of that was an excessively small object. 



Dr. Lawson inquired whether the ordinary system of measurement 

 could be adopted in Mr. Gayer's instrument. 



Mr. Gayer replied he believed it could. With regard to the dis- 

 persive power of the instrument he had described, there were two 

 prisms in the tube, and it would be optional for anyone to have either 

 of them. 



Mr. Wenham said he thought the micro -spectroscope should be 

 made more universally to bring out Fraunhofer's lines fully. The 

 arrangement Mr. Gayer had introduced would effect that object far 

 more perfectly than the form of spectroscope generally used. 



Mr. Ingpen said he could bring out Fraunhofer's lines beautifully 

 with Browning's small spectroscope. 



A vote of thanks was given to Mr. Gayer. 



Dr. Boyston-Pigott read a paper " On a New Method of Using a 

 Micrometer." 



Mr. Wenham said he thought it was very desirable to get an 

 aerial image with a distant micrometer in the same plane with the 

 object ; because in that case you can dispense with extra surfaces in 

 the eye-piece. If he understood Dr. Pigott correctly, he has attained 

 that end. 



Dr. Pigott assented ; a vote of thanks was unanimously accorded 

 to him. 



The President then read a paper " On the Histology and Growth 

 of the Skull of Tit and Sparrow-Hawk." 



A vote of thanks was passed to the President for his interesting 

 paper. 



Donations to the Library, from Nov. 6th to Dec. 4th, 1872 :— 



From 



Land and Water. Weekly The Editor. 



Nature. Weekly Ditto. 



Athenseum. Weekly Ditto. 



Society of Arts Journal. Weekly Society. 



Quarterly Journal of the Geological Society, No. 112 Ditto. 



The Microscopical Theatre of Seeds. By James Parsons. Yol. 1, 



1745 Dr. Millar. 



Royal Society's Catalogue of Scientific Papers. Vol. 6 . . . . Royal Society. 

 On the Natural System of Botany. By Benjamin Clarke, F.L.S., 



1866 " Author. 



On New British Graptolites. By Johu Hopkinson, F.G.S Ditto. 



Walter W. Beeves, 



Assist.-Secretary. 



