1086 PROCEEDINGS OF THE SOCIETY. 



No. VII. immersion and amplifier (concave lens). Distance 1 metre, 

 central illumination. 



2. PJeurosigma angulatum — the same frustule magnified direct 

 5900 times with Gundlach's No. VII. immersion and amplifier. 

 Distance 3 metres, central illumination. 



3. Frustulia saxonica, showing lines parallel to the axis of the 

 frustule, magnified direct 5000 times with Seibert and Krafi't's new 

 oil-immersion objective. 



The existence of these lines parallel to the axis of the diatom is 

 quite new, and I think many of the Fellows will be interested to hear 

 of it. It seems as if all drawings on all diatoms come back to crossed 

 lines or circles, and as soon as one sort of lines can be seen the 

 existence of others crossing the same can be guessed. 



We are now trying to find these crossed lines in AmpMjpleura 

 pellucida. 



All the photographs were made by Carl Gunther, of Berlin." 



Mr. Jno. Mayall, jun., said it was very interesting to compare the 

 lithographs published in the 'Monthly Microscopical Journal' (1876) 

 of Dr. Woodward's photographs of Frustulia saxonica with those now 

 shown. Dr. Woodward was at first doubtful as to the existence of 

 both transverse and longitudinal lines, but Mr. Samuel Wells, of 

 Boston, afterwards showed them very distinctly, though not so well 

 as they were shown in the photographs before the meeting. 



Professor R. Hitchcock's letter was read as to the publication of 

 Mr. Habirshaw's ' Catalogue of the Diatomacese ' if a sufficient number 

 of siibscribers were obtained. 



Mr. Crisp exhibited and described the following nine Microscopes : 

 — Beck's Silk Mercer's, Swift's ditto, Holmes's Demonstrating, Nachet's 

 " Snufi" Box," Parkes's English Medical with sliding adapters for the 

 objectives (see p. 1048), and a small form of simple Microscope with a 

 mirror made in Paris. He also exhibited a Nachet Microscope to 

 which the " Thury-Nachet Traverse Substago" (see p. 1059) had 

 been attached, Sidle and Poalk's Acme Microscope with Iris Dia- 

 phragm (see pp. 532 and 1053), and the Tolles-Blackham Microscope 

 (see p. 520). 



Dr. W. B. Carpenter, C.B., exhibited and described the " Working 

 Microscope " devised by Mr. George Wale, an American manufacturer 

 (see p. 1045). Being struck by the novelty of several parts of the 

 instrument, he had thought it worth while to get one, and he had 

 no hesitation in saying, after working with it, that it combined more 

 good points than any student's Microscope which he had yet seen. 



The first point was the method of susj^ension, which, instead of 

 being on the usual plan of a swinging centre with two pivots, con- 

 sisted of a grooved arc moving between corresponding curved fillets 

 on a central support ; the foot was of cast iron (together with the 

 arc carrying the body), and was made in two pieces, on each of 



