MICROSCOPY. 



519 



and abandoned. They were limited, however, 

 to four and in most cases to two objectives, 

 were rather costly, and their weight with that 

 of even two attached objectives impaired the 

 usefulness of many forms of fine adjustment. 

 A later and doubtless better device, of which 

 more than a dozen varieties have been intro- 

 duced, and many of them patented during the 

 last four years, is an adapter to screw perma- 

 nently into the nose-piece of the microscope ; 

 of such construction that any objective may 

 be instantly attached or released, the objective 

 in most cases requiring a specially adapted 

 collar to be worn upon its " Society " screw. 

 Several of these are friction-catches, that of 

 Mr. Parkes, published in 1880, having upon the 

 top of the objective a cylindrical tube which 

 could be slid firmly into the split tube of the 

 adapter. Mr. Frank Crisp immediately pro- 

 posed the substitution of the conical fitting 

 adopted by Mr. Browning for astronomical 

 eye-pieces; which was accomplished by Dr. 

 Matthews, of the Quekett Club, three years 

 later. Still later Watson & Son. for greater 

 safety, slit the outer cone and surrounded it 

 with a screw-collar for gripping the objective. 

 The conical form is extremely simple, adds but 

 little to the length of the body, and possesses 

 much greater capabilities of cheapness than 

 any other. When properly handled its power 

 of attachment is practically unlimited ; but its 

 proper insertion and easy removal depend upon 

 the constant care and skill of the user. In an- 

 other class of adapters the objective is slipped 

 sidewise under a shoulder at the bottom of a 

 sliding-tube or under the prongs of a horizon- 

 tal fork, and held up against the nose-piece by 

 a spring. Such are the " objective-carrier " of 

 Nachet, the "objective-extractor" of V6rick 

 and the " Geneva nose-piece," by the Societ6 

 Genevt)ise pour la Construction d'Instruments 

 de Physique. Of these, which are especially 

 applicable to the small Continental objectives, 

 the Geneva adapter was doubtless the pioneer, 

 being designed by Prof. M. Thury in 1863, and 

 with some modifications exhibited by the Ge- 

 neva company at the Paris exhibitions of 1867 

 and 1878, and was the only one known until 

 after that date. It attracted little attention, 

 however, and at present the modification by 

 M. Nachet (Fig. 36) seems to be by far the 

 most generally known and used, as well as 

 very satisfactory in practice. In another class 

 the bayonet-catches are revived, as in one of 

 Mr. E. M. Nelson's adapters, and in Mr. Bui- 

 loch's devised and proposed by Prof. Albert 

 McCalla, in each of which three projecting 

 pins upon the collar are safely locked within 

 the adapter. Cutting away alternate sections 

 of the " Society " screw thread from the ob- 

 jective and nose-piece, so that the former can 

 be inserted without screwing, and locked in 

 position by a slight turn toward the right (a 

 device long familiar in the arts of peace and 

 war) was proposed for the microscope by Mr. 

 Vogan in " Science Gossip," and introduced by 



Mr. E. M. Nelson at the Quekett Club in 1882. 

 Mr. Zentmayer in his very practical form placed 

 the divided screw on the outside of a " Socie- 



FIG. 36. NACHET'S 

 NOBE-PIECE. 



FIG. 37. ZENTMAIEB'S 

 NOSB-PIECE. 



ty " screw collar, and furnished an adapter to 

 match, as shown in Fig. 37, thus obviating 

 any alteration to the objective or microscope. 

 Meanwhile, the nose-piece was made by Jas. 

 L. Pease, of Chicopee, Mass., as a mechanical 

 chuck with power to grasp a collar on the ob- 

 jective. Mr. Thomas dirties, of London, add- 

 ed a " Society " screw thread to the jaws, so 

 as to clasp the objective without a collar ; and 

 Mr. Charles Fasoldt, of Albany, N. Y., greatly 

 simplified and improved the apparatus by mak- 

 ing one only of the jaws movable and con- 

 trolled by a spring and lever, as shown in Fig. 

 38. With this adapter upon the microscope, 



FIG. 38. FASOLDT'S NOSE-PIECE. 



the formerly tedious procedure of attaching 

 and detaching objectives is reduced to simply 

 touching a lever while placing the objective 

 where it is wanted. 



Objective protectors, to enable the micro- 

 scope to be used with the lower portion of its 

 tube plunged into the liquid containing the ob- 

 jects to be examined, seem to have been origi- 

 nally invented by Dr. C. E. Goring, who de- 

 scribed (" Micros. Illust.," London, 1829, p. 174) 

 a modification of his " engiscope," having the 

 compound body prolonged downward below 

 the transverse bar sufficiently to reach near the 

 bottom of a small aquarium-jar ; the submerged 

 portion of the tube being protected by a glass 

 tube or " boot," closed at the bottom just be- 

 low the objective by a piece of plate-glass. A 

 " diagonal boot " was also provided with a 

 mirror set just below the objective at an angle 



