230 



SUMMARY OF CUKEENT RESEARCHES RELATING TO 



catalogue that lie was making all Cuff's models in 1771. "We also have 

 in ElHs's work on the Corallines (1755) a description of the aquatic 

 Microscope Cuff made for him. So it has been customary to fix the 

 date of Cuff's retirement from business between the years 1755 and 1771. 

 But obviously the publication of Ellis's work in 1755 does not imply that 

 his Microscope was made in that year ; on the contrary the probability 



Fig. 30. 



is that it was made much earlier, aud that Ellis had been working with 

 it some years in the preparation of his book. Similarly Adams may 

 have made Cuff's Microscoj)es some time before the pubHcation of his 

 1771 illustrated catalogue. The discovery of this dated Microscope 

 affords, therefore, strong evidence that Cuff must have given up business 

 or died before 1751. The uamC S. Johnson is engraved on the stage 

 plate, and it is almost certain that this Microscope was the property of 

 the celebrated Dr. Johnson. 



