556 



Notes. 



Mr. Jackson, viz. the substage slide was made in one casting with the 

 limb, and the rabbetted grooves both for the body and substage were 

 ploughed in one cut. Fig. 151 is the earliest figure extant of this kind 

 of Microscope. It will be observed that in this Microscope no center- 

 ing gear is attached to the substage, because it was thought that the 

 Jackson ploughed groove rendered such an appliance superfluous. 

 This instrument was also mounted upon Jackson's trunnion and double 



Fig. 151. 



pillar (this was afterwards arranged so that the flat tripod foot could 

 be rotated beneath the pillars) ; a concentric rotating mechanical stage 

 was added ; and after 1860 the single body was exchanged for the 

 Wenham binocular. In 1873 one of these Microscopes, which is 

 frequently used at our Meetings,' was presented to the Society by 

 Mr. Charles Woodward. Fig. 152 is taken from E. L. Beck's 

 Achromatic Microscope. 



In 1852, Mr. Joseph Beck joined the firm, which then became 



