PROCEEDINGS OF THE SOCIETY. 245 



Dr. Charles Singer was particularly interested in the President's 

 suggestion that Conrad Gener had figured a magnified image of a 

 Foraminifer as early as ISCio. The reference was quite new to the 

 speaker, and must be by far the earliest of the kind yet unearthed. It 

 was extraordinary that though convex spectacles, often of considerable 

 power, were in use from about the year 1300, they seem never to have 

 been used in investigating minute Nature. Yet want of interest in 

 natural phenomena can hardly be charged against such men as Leonardo 

 da Vinci, Albrecht Durer or Bernard Palisez ! 



He also drew attention to Manzini's book (" L' occhiale all' occhio, 

 Dioptrica pratica "), of 1660, placed on the table by the President, which 

 which was one of the few early works dealing with the manufacture of 

 lenses, a process which was to a large extent a trade secret. The work 

 was valuable as revealing the methods of Eustachio Divini, one of the 

 first great microscope-makers. Lenses in the early part of the 17tb 

 century were a very costly luxury. As much as the equivalent of £50 

 would sometimes be paid for a good pair of spectacles. Martin's double- 

 adjustment Microscope was mentioned as being the first of its kind, and 

 stress laid on the importance of a substage condenser in the production 

 of a clear image. A Microscope, however, was figured by Zahn (1685) 

 and by Bonani (1709) as having belonged to Athanasius Kircher (1601- 

 1680). This instrument was probably in use before 1658 and had both 

 a coarse- and a fine-adjustment, as well as an apparatus corresponding to 

 a substage condenser. A substage condenser also formed part of the 

 curious Microscope figured by Descartes in his " Dioptrique " as early as 

 1637, which figure was the first yet discovered of an actual compound 

 instrument ; though Galileo already in 1610, and Kepler in 1611, 

 published diagrams of the path of light in such an instrument. Dr. 

 Singer was glad to hear that the Royal Microscopical Society was con- 

 sidering the preparation of a History of Microscopes and Microscopy. 

 Such a work was greatly needed. 



Mr. Ainslie regarded this as one of the most striking exhibitions, 

 both of mounts and Microscopes, that he had ever seen or heard of, 

 and he wished to be allowed to congratulate the Royal Microscopical 

 Society thereon. He commented on the fact that very little was said 

 in the paper about the advent of the substage condenser. The 

 Foraminifera were all shown under low powers, and for such the 

 substage condenser would not be a very striking improvement. But it 

 was due chiefly to the substage condenser that the Microscope has 

 shown such marked improvement. Non -achromatic objectives might 

 have been made of large aperture, and used with monochromatic light 

 — as had been done in the Zeiss quartz objectives, for use with ultra- 

 violet light — but as Dr. Dallinger said, " without a condenser a Micro- 

 scope is merely a magnifying-glass ; with one, even if it is only a 

 hemispherical lens in a stage-plate, it becomes a scientific instrument." 

 He had also hoped to have heard something about the improvement of the 

 image due to the employment of a larger cone of illumination than 

 could be obtained from a concave mirror. He was interested in the big 

 Powell Microscope, and would ask if the objective shown on the stand 

 was an " inch," and of the same date as the stand. John Marshall's 



April 19th, 1910 S 



