PROCEEDINGS OF THE SOCIETY. 
95 
King’s College, April 3 , 1878 . 
H. J. Slack, Esq., President, in the chair. 
The minutes of the preceding meeting were read and confirmed. 
The list of donations was announced, and the thanks of the 
Society returned to the respective donors. 
The President gave notice that upon the recommendation of Mr. 
Stephenson, Dr. Matthews, and Mr. Crisp, in accordance with the 
fifteenth bye-law, and with the approval of the Council, Professor 
Abbe, of Jena, had been duly nominated an Honorary Fellow of the 
Society, and that accordingly the Professor’s name would be suspended 
in the usual way and submitted for election at the meeting of the 
Society in May. 
Mr. J. W. Stephenson read a paper “On a New Large-angled 
Immersion Objective without any Adjustment Collar.” 
The President said that Mr. Stephenson had been kind enough to 
bring down to the meeting the object-glass which he had described 
in his paper, and another of the same pattern belonging to Mr. Crisp 
was also in the room, and it would be, no doubt, interesting and useful 
to examine them after the meeting. 
Mr. Frank Crisp said that he could bear testimony to two, at any 
rate, of the advantages of the new objective, viz. the great increase of 
light, and the facility with which it could be at once adjusted to the 
object, being without correction collar. It might be interesting to 
observe, by way of history, that the use of oil in Mr. Stephenson’s 
objective had nothing in common with the use of it for microscopical 
purposes by Sir David Brewster in 1810 — before the application of 
achromatism to the microscope. His plan was to place the object to 
be observed at the bottom of a small glass cylinder filled with oil, 
and the objective was focussed upon the object through the oil. 
There was thus a convex lens of crown glass, and the oil acted as a 
concave lens. If the proper curves were taken for the convex lens, 
there would in the result be (theoretically) an achromatic combina- 
tion. 
Dr. Matthews thought that the discrepancy observed as to the 
tables of refractive indices, to which allusion had been made in the 
paper, might be due to the age of the oil. All essential oils under- 
went oxidation, which caused them to become thicker and more 
refractive, and this might account for the discrepancy. 
The President inquired which of the essential oils was least 
subject to this kind of alteration. 
Dr. Matthews was hardly prepared to say without looking into the 
subject more closely, but he believed the worst was turpentine. 
The President said it was clear that the chief consideration in 
the case of this objective was to get the proper kind of oil. 
The thanks of the meeting were voted to Mr. Stephenson for his 
paper. 
Mr. Frank Crisp read a paper “ On the Present Condition of 
Microscopy in England.” 
The President thought that Mr. Crisp had hardly been quite fair 
to Dr. Pigott in the course of his observations. Dr. Pigott only 
