312 



SCIENCE. 



[Vol. X. No. 255 



pupils and teachers were speaking a language which he could 

 scarcely understand. He would also find that it was a common 

 thing for a teacher to demonstrate to his pupils with actual 

 specimens, day after day, things which in his own day it was 

 utterly impossible to demonstrate except by the most laborious and 

 roundabout methods, and which at best gave unsatisfactory results. 

 With this enormous advance in technique or in the processes of re- 

 search, has arisen a demand for a better class of laboratory instru- 

 ments, which, while they are compact, simple, and of moderate 

 height and weight, are constructed with a view to durability, and 

 at the same time admit of use for all the ordinary purposes of the 

 investigator or student. Such instruments should possess such 

 qualities as would enable one to use them for the most elementary 

 as well as for the most advanced work requiring the highest grade 

 of manipulative skill. The senseless catering of makers to the 

 lovers of ' brazen elephantiasis' (as 1 once heard an eminent histol- 

 ogist express himself), with their large and costly instruments, has 

 wrouo-hta kind of mischief which teachers have every now and then 

 to contend against, in the tendency of poorly informed tyros buying 

 at large cost these brazen giants, which they soon find are not what 

 they want. 



My own deliberate conviction is, that the ideal microscope for 

 the student and investigator still remains to be devised ; that neither 

 Europe nor America has yet produced it ; and that any attempt to 

 produce such an instrument, v/ithout considering every possible and 

 reasonable demand that can ever be made of it as a table micro- 

 scope, must end in failure. Looking over the vast amount of rub- 

 bish which is constantly being figured in microscopical journals as 

 something new and valuable, one is often tempted to make the 

 ■comment, " Why could not that person have been more usefully em- 

 ployed than in devising that perfectly useless piece of apparatus .' " 

 There are, however, many exceptions ; and I do not mean to be 

 understood as scolfing at all new pieces of apparatus, because 

 many of them first devised within the last ten years have been of 

 the greatest value. 



How is this ideal microscope to be realized ? Who will design 

 it, and who make it after it is designed ? I would suggest that 

 ■every piece be made to a standard gauge, and that thus, if any 

 parts are broken or worn out, they may be replaced with a mini- 

 mum of trouble. I would advise that the existing rack and pinion 

 be replaced by a better construction, as no rack and pinion yet 

 made is so constructed as to remain firm and steady after prolonged 

 use of the instrument. The fine adjustment can be made a part of 

 the coarse adjustment, provided the cogs of the rack and pinion are 

 accurately cut ; and this adjustment can be placed at the back of 

 the instrument, near the fingers of the manipulator. In this way a 

 source of weakness in the construction of both American and foreign 

 instruments may be avoided. The outside tube in which the opti- 

 cal tube slides must be fixed, and form a part of its support. The 

 optical tube must be short ; tube length, with draw-tube out, not 

 over 155 millimetres, so as not to make the instrument uncomfort- 

 ably high when the tube is vertical. The support for the tube must 

 be in a single, solid piece, which may also support the simple, flat, 

 wide stage covered with a thin piece of hard rubber firmly fastened 

 to its upper surface. The stage clips must be so placed that they 

 do not interfere with moving the slide ov«r the whole width of the 

 stage. The base or tripod upon which the whole rests must be cast 

 in a single piece, and the joint at the back, between the base and 

 the supporting piece for the tube, to be made simple and strong, 

 and so that it may be quickly tightened by the manipulator if it 

 should get loose. This joint for tilting I hold to be necessary for 

 certain kinds of work and for photography. The mirror bar must 

 be large and strong, and made as nearly concentric with the surface 

 ■of the stage as possible. The attachment for the condenser should 

 be made so that it is firm, and so that the condenser is easily swung 

 into and out of position, and rapidly adjusted up or down with as 

 little accessory mechanism as possible. A condenser of the Abbe 

 type is of course the only one to be considered for general work, 

 and it should be as short as possible, so as to make it possible to 

 keep the stage as low down or near the table as is consistent with 

 ready and successful illumination. The concave mirror should be 

 larger than on the most of the laboratory microscopes used here 

 and abroad. 



Now a word as to the camera lucida. This absolutely necessary 

 piece of apparatus must be adjustable to every eye-piece, and it 

 should be available for use with the tube upright, inclined, or 

 horizontal, without the addition of any desks or drawing-boards to 

 the outfit of the microscope. If the rack and pinion is properly 

 constructed, and an adjustable or sliding collar with the Royal 

 Society screw fitted into the optical tube or body, with this camera, 

 and a proper combination of eye-pieces and long or short focus ob- 

 jectives, drawings of objects may be made, ranging from 5 to 1,500 

 diameters, without difficulty, and the use of an embryograph largely 

 if not entirely dispensed with. Searcher eye-pieces might be added 

 to the combination, which would make the outfit still more com- 

 plete and varied for the use of the investigator who needs to make 

 figures of the subjects which he studies. 



It will thus be seen that the prime requisites in the microscope 

 for the investigator are simplicity and mechanically correct con- 

 struction. No instrument yet made fulfils in the largest possible 

 measure these requirements. Mr. Zentmayer has really added im- 

 portant improvements to the instruments constructed in this coun- 

 try ; and for solidity and fewness of pieces, his work (which has 

 always been honest) has been among the very best. American 

 observers of world-wide reputation have used American instruments 

 and objectives with success. Among these may be mentioned men 

 no less famous than Profs. H. James Clark, Alpheus Hyatt, and 

 Joseph Leidy, while Prof. J. F. Rothrock's studies with American 

 lenses upon the strength of wood as illustrated by sections has 

 started a most important line of practical inquiry. 



But notwithstanding this, as stated at the beginning, the ideal 

 microscope is still to be placed upon the market. To have the 

 matter assume the importance which it demands, I would suggest 

 that the American Society of Naturalists, at their next meeting, 

 take into consideration the question of securing a satisfactory de- 

 sign for a standard instrument. Let this be done by offering a 

 prize to be competed for, and let us for once have something like 

 uniformity of pattern in this most important instrument of re- 

 search. The teacher would then have no difficulty in suggesting to 

 his pupils what make of microscope they should buy, and every 

 maker would not be offering instruments departing more or less 

 from a recognized standard. 



And finally, as suggested by Dr. W. P. Wilson, now that the 

 surplus from revenue and tariff is stirring the political wiseacres at 

 Washington, where a plethoric treasury is threatening the financial 

 prosperity of the country, let our universities and colleges make an 

 appeal to members of Congress, in co-operation with the American 

 Society of Naturalists, to have the absurd tariff on imported scien- 

 tific books and apparatus removed. This senseless tax on knowl- 

 edge, which it seems is to be catalogued among the 'luxuries,' is a 

 glaring and shameful disgrace to American institutions. As it is, 

 neither American publishers nor manufacturers are profiting to any 

 extent from this absurd regulation, nor are they likely to, even 

 after the duties are removed. John A. Ryder. 



University o{ Pennsylvania, Dec. 15. 



Sound-Blindness. 



In Science for Nov. i8, p. 244, I observe some remarks on cer- 

 tain phenomena of defective hearing, which, from their supposed 

 analogy to color-blindness, is called ' sound-blindness.' I am very 

 much interested in the facts, but the name I do not at all like. It 

 seems to me very misleading. But neither is the term ' sound-deaf- 

 ness,' which was proposed as a possible substitute, any better. 

 Comparing the eye and the ear, 'sound-deafness ' corresponds with 

 ' light-blindness ; ' but these terms express simply blindness and 

 deafness without qualification. The correspondent of color-hXvcidi- 

 ness is not io««rf-deafness, but ///ir/i-deafness. But the phenome- 

 non spoken of in the article referred to is neither sound-&t.2Axits& 

 nor /z'^^/i-deafness ; for the characteristic of vowel-sounds is not 

 musical pitch, but timbre. In so far as the phenomenon is physio- 

 logical at all, the defect is therefore /z>«(5r^-deafness. But it seems 

 to me that the defect is probably, largely at least, a defect of per- 

 ception, and not of sensation, and therefore psychological, not physi- 

 ological. Joseph LeConte. 



Berkeley, Cal., Dec. g. 



