244 PROCEEDINGS OF THE SOCIETY. 



it seemed to be so ; but it had to be remembered that John Ellis only 

 used low powers for his special work, and those low powers had to be used 

 on organisms in fluids, and the instrument had to be placed in an erect 

 position. Ellis made suggestions to Cutf, who made a Microscope, now 

 known as the Ellis Aquatic Microscope, first figured and described in 

 1755. In "An Essay towards a Niitural History of the Corallines" 

 (1755), Ellis says : " In August 1752 I went to the Island of Sheppey 

 on the Coast of Kent, taking with me a very commodious Microscope of 

 Mr. Cuff's, the Optician in Fleet Street, which I had altered for that 

 purpose." Mr. Court considered this to have been the type from vv^hich 

 p]llis"s Aquatic Microscope was developed, and in this opinion Mr. Nelson 

 agreed. Later he had come across an original advertisement by Cuff, 

 in which he advertized this Microscope as an aquatic Microscope. In 

 1758 it was further ifiiproved l)y the addition of a compound body, and 

 in other small details : the original descriptive pamphlet of this newer 

 model was entitled, " The description of a single and double microscope 

 very convenient to observe all sorts of objects. London, printed by 

 U. Pardon in Castle Yard, Holborn : 1758." DoUond also made the 

 Hllis A'juatic Microscope about 1705, and in the printed description calls 

 it the arjiiatic Microscope as improved by John Ellis, F.R.S. 



Mr. Earland then drew attention to the points of interest in the 

 various Microscopes which had been removed from the Society's col- 

 lection in order to illustrate the paper, commencing with the little 

 Leeuwenhoek, which was a model of the original, presented by Sir 

 Frank Crisp. Leeuwenhoek, he said, no doabt saw most remarkable 

 things through the lenses which he made for himself from little spheres 

 of glass, but the definition of the reproduction was very poor. In the 

 Lieberknhn model there was really excellent definition. It was a 

 troublesome model to adjust, as there was no means of locking the 

 specimen when focused. But once focused and properly adjusted for 

 light, remarkable definition was obtained, and, except for the small size 

 of the image, it was as sliarp and clear as with a present-day lens. There 

 was, in his opinion, no improvement in the definition of the image from 

 this point onwards until the reflecting type of instrument was reached. 

 Some of the models fell below the general average as regards sharpness 

 of definition. The first real improvement was found with the introduc- 

 tion of the substage condenser, and when the reflecting Microscopes 

 were reached there was an absence of colour, and a consequent increase 

 in the definition of the image ; an improvement which was increased by 

 the fact that about the time the achromatic lens was invented balsam- 

 mounting came in. There was no compari-on between the image 

 given by such a combination and any of its predecessors. 



In conclusion, he would like to add to what the President said in 

 regard to the indebtedness of the Society to Mr. Court. Owing to the 

 regrettable illness of Mr. Rousselet the bulk of the preparation for the 

 demonstration had fallen on Mr. Court, and but for him there could have 

 been no exhibition, because even to manipulate' and setup these old types 

 would have been beyond the powers of the speaker or any other 

 microscopist who was not deeply skilled in the lore of the antique 

 Microscope. 



