134 



of Mr. Sollitt's method. Mr. Stephenson, adopting the same system, places 

 two flames, such as night-lights, at known distances apart, and using the 

 objective alone without any tube, has a very convenient scale of tangents 

 engraved upon paper, thus showing the angle by inspection. This is des- 

 cribed in the Month. Mic. Journ., July, 1875, p. 3. In the Month. Mic. Journ. 

 for May, 1874, p. 178, Mr. Wenham describes an adjustable slit formed by 

 two slips of very thin platina foil, which can be separated to the exact 

 diameter of any field of view, thus excluding all but " image-forming rays."* 

 This is a very valuable adjunct, and greatly conduces to accuracy ; and when 

 used with a divided circle, with small flames at a suitable distance, or white 

 crosses on a black ground, and with a lens or lenses centred and sliding 

 above the eyepiece, it forms a very suitable and accurate combination. 

 — Mr. Ingpen concluded with some general remarks upon the subject of 

 angular aperture, with reference to the various opinions held upon this 

 somewhat vexed subject. 



A vote of thanks to Mr. Ingpen for his communication was unanimously 

 passed. 



The President thought that one of the most important points in connec- 

 tion with the subject was that the rage for large angular apertures had given 

 the impression in some quarters that good low-angled objectives could not be 

 made by English makers, and therefore foreign makers had stepped in and 

 produced them; whereas, if there were a demand for low angles, they 

 could be produced here with all the excellence which was usiially found in 

 English workmanship. He thought that the observations they had just 

 heard had a very useful tendency, and would be valuable to those who did 

 not make the microscope a mere toy. 



The proceedings then terminated with a conversazione, at which the fol- 

 lowing objects were exhibited: — 



Marine Algse — in fruit by Mr. T. Curties. 



Polyommatus phlceas, male ... ... ... ,, Mr. Enock. 



Allosopus calomelanos ... ... ... ... „ Mr. Golding. 



Aphis Galls on leaf of hedge maple ... ... „ Mr. E. T. Lewis. 



Spiral Vessels of Castor Oil Plant „ Mr. Martinelli. 



Podura Scale — with 1-6 in. objective „ Mr. Swift. 



Ova of Toad— injected „ Mr. Topping. 



Anchors and Plates of Synapta „ Mr. Jas. Watkins. 



Phtirius inguinalis — or crab louse ... ... „ Mr. T. C. White. 



Attendance — Members, 60 ; Visitors, 8 ; Total, 68. 



* See also M.M.J. , for March 1, 1874, p. 114. 



