1062 SUMMARY OF CURRENT RESEARCHES RELATING TO 



tube is the megaloseopic telescope consisting of an objective and 

 an eye-piece of suitable power. 



The advantages of this arrangement are first, that the adjustment 

 for the eye of each observer is made externally by the eye-piece, and 

 therefore all internal mechanism is suppressed. This allows, more- 

 over, a second eye-piece of much greater power to be substituted for 

 the first eye-piece ; the mucous membrane and its lesions are then ob- 

 served as with a magnifier. Second, adjustment for focus, properly 

 so called, is nil. This proposition which is not theoretically exact, 

 is so, however, practically. The reduced image formed in space, 

 being displaced by a very small quantity only in proportion to the 

 greater or less distance of the object, the focal adjustment may be 

 neglected ; the eye of the observer itself makes unconsciously its 

 proper adjustment for focus, and the different parts of the mucous 

 membrane situated at different planes are thus seen in their entirety 

 with the same clearness — a point of first importance. 



For the bladder and the rectum the tubes are straight. For the 

 stomach there is a double tube ; one with an elbow has a prism 7 cm. 

 long, placed between the reduced image and the telescope ; the 

 other is straight and passes into the former, and its movements of 

 elevation, depression, or rotation are governed by exterior mechanism. 



A further improvement, which is in contemplation, is the photo- 

 graphic reproduction of the megaloseopic image. 



Finally, this instrument shows that the result obtained is and will 

 always be the same, however long may be the tube at the extremity 

 of which the reduced image is formed, or whatever may be the dis- 

 tance of this image from the telescope and the eye of the observer." 



The apparatus of M. du Eocher appears to be identical with that 

 described * by Herr J. Leiter, but there is no acknowledgment of his 

 priority in the matter. 



Watson's Swingeing Substage Microscope. — Messrs. W. Watson 

 and Sons have modified their large stand f which now has the form 

 shown in fig. 236. It has a rotating base plate, mirror arranged to 

 swing either above or below the stage (with graduated circle), and 

 patent concentric rotating stage. 



The fine adjustment is upon the Zentmayer principle, in which 

 the coarse adjustment slide is carried by the fine adjustment slide, 

 and the whole moved together by a lever acted on by a micrometer 

 screw. The peculiarity of Messrs. Watson's construction is in the 

 application of adjustable slide bearings to the original form of arrange- 

 ment. For this purpose they have made the fine adjustment slide 

 much broader than usual, thus increasing its stability ; the prism 

 bars also not only slide in grooves on the main surfaces of contact 

 of the bearings, as in Bulloch's and other forms, but the bearings are 

 carried round the outer prismatic edges of the whole length of the 

 main slides, and adjustable screws are applied by which the friction 

 on these edges can be regulated. 



* See this Journal, iii. (1883) p. 421. 



t For the original form see Engl. Mech., xxxii. (1881) pp. 487-8 (1 fig.). 



