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" Challenger Reports," Vol. v.,.. ... ... Purchased. 



" Catalogae of Fossil Foraminifera in British ) 

 Museum" ... ... ... ... ) 



"Annals of Natural History " ... 



" Coles' Natural History Studies/' 19 to 24 ... 



'* Dippel's Treatise on the Microscope " 



Two Slides of Diatoms ... ... ... ... From Dr. Partridge, of 



Stroud. 



The thanks of the Meeting were voted to the Donors. 



Mr. E. M. Nelson exhibited and described Zeiss's dissecting microscope. 



Dr. Ramsden enquired whether the instrument was capable of resolving 

 the striae on Navicula Lyra into dots ? 



Mr Nelson said no ; but it would show the striae. 



Mr. Ingpen could fully confirm all that Mr. Nelson had said as to the 

 merits of these lenses, having been in the habit of using them for some 

 time. He had not seen the low power one before, but welcomed it as a 

 very useful addition to the series. He had always advocated the use of 

 good lenses where low powers were required, although often told that a 

 common watchmaker's eye-glass was all that was wanted for dissecting 

 purposes ; theoretically, however, it could be proved that an achromatic 

 lens was necessary, and he thought they were much indebted to Mr. Zeiss 

 for bringing out lenses of this kind, and thus enabling them to save their 

 eyes as much as possible. With his own defective vision he found he could 

 do ten times the work with one of these lenses that he could with a common 

 glass, and he was quite sure that there was a very great saving of the eyes 

 in using glasses of this sort. 



Mr. T. C. White inquired what was the working distance in the case of 

 the smaller of the two microscopes exhibited, because if it were only a iin. 

 or even ^in., he thought it would be rather difficult to work under. He 

 quite agreed with the opinion that it was a necessity to have good lenses to 

 dissect with. He had lately been using Stephenson's binocular with its 

 erecting prism, and being engaged on a paper upon the salivary glands of 

 insects, he had been making a number of small dissections, such as the 

 salivary glands of a flea, and the importance of getting the object near to 

 the head was very much impressed upon him — if it was a long way off the 

 operator was very apt to get the needles in the wrong place. 



Mr. Nelson said that the focal distance of the lens was -fV n - w ith the 

 eyepiece, and gave a power of 100. Without the eyepiece the focus was 

 considerably shortened, although the power was reduced to about 20. A 

 watchmaker's lens of the same power would be considerably shorter. 



Mr. T. C. W T hite asked if the lens gave a good field of view ? He thought 

 the requisites for a dissecting microscope were a good field, good definition, 

 and that the object should be near at hand. 



Mr. Ingpen said at first sight the field seemed to be extremely small, but 

 if the eye were put close down to the eyepiece it would be found that by 

 looking sideways a good sized field could be obtained. If they wanted to 



