M. NELSON ON THE EVOLUTION OF THE MICROSCOPE, 



351 



above is a remarkable instance of straining out a gnat and 

 swallowing a camel (Fig. 2). 



The next important step is the application of a field lens to 

 the eye-piece by Monconys and Hooke. Monconys' microscope 

 was made in 1660, an account of it being published in 1665. 

 The application of a field lens was also claimed by Hooke, who 

 in 1665 published an account of his microscope.* Hooke's 

 microscope is a very important one, for in it we find several 

 new features, such as the inclination of the body, a screw 

 focussing adjustment, a movable object-holder, and an entirely 



Fig. 3. 



novel illuminating apparatus. In Fig. 3 we see a heavy 

 circular foot, p, with an upright post, 6, fixed excentrically to it. 

 The limb which holds the body of the microscope is attached 

 to the post by a sliding ring, o, and screw clamp. The limb is 

 also jointed by a ball and socket. At the other end of the limb 

 is a ring, d, into which the body screws with a coarse thread. 

 This forms the fine adjustment. The body, a, was fitted with 

 four draw tubes. This form of mounting for the body of a 

 microscope I call the " telescope mount," for the microscope is 

 pointed at the object precisely in the same manner as a telescope 

 would be. There is an ingenious object-holder, r, consisting of 

 a spike capable of rotation, held by a short pillar attached 

 excentrically to a rotating disc. This disc is held in position 



* Mr. Mayall, jun., was of opinion that Monconys' invention preceded 

 that of Hooke. Cantor Lecture, Society of Arts, Feb. 27th, 1888. 



