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HARDWICKE'S SCIBN CE-GO S S IP. 



to correct the false impression made upon the eye 

 while following the motion of the hand ; and thus 

 the knife, camel-hair pencil, or bristle, is placed at 

 once upon the particular portion of the object 

 required, and moved about as desired. Having thus 

 become used to work with the compound instru- 

 ment and inverted image, I think I may safely 

 affirm that the same difficulty is experienced when 

 the erecting-glass and direct image are used. I 

 must candidly admit that it is so with myself, for 

 after using the compound instrument without an 

 erector for the last twenty years, I am completely 

 bothered when I have tried to use one ; and even 

 now, as lam using my instrument — with the erector 

 I am about to describe — I have the greatest diffi- 

 culty in placing the object in its proper position or 

 in shifting it the right way for direct image, and 

 no doubt many others find the same difficulties. 

 Of course, all microscopists know that ereeting- 

 glasses, to fit in the body of the instrument, and 

 erecting-prisms to fit over the ocular, are sold by 

 opticians or supplied with the instrument ; but I 

 think that very few are aware that an equally good 

 erector — in one respect, at least, superior — is 

 ■within their reach, and that without any outlay or 

 expense whatever. It is effected by placing an 

 objective inverted, over the ocular, — or, in perhaps 

 more simple language, placing an object-glass 

 upside down over the eye-piece. I find that a 

 i-inch ( X 190) answers this purpose very well, but 

 a i-iuch or §-inch may be tried with advantage. I 

 am writing this article at sea, and my best instru- 

 ment and whole range of best object-glasses are at 

 home, so I have only my working instrument and 

 two powers — a combination of 1-inch, J-inch, and 

 i-inch— with me, and am unprepared to say from 

 actual experiment what may be the best powers 

 to use ; but so far as I have experimented, I find 

 that a low-power objective in the nose-piece of 

 the instrument (an A ocular, and a i-inch objective 

 over the ocular) to be about the best combination. 

 The more so, as the superiority 1 claim for this 

 erector, and to which I alluded before, consists in 

 its acting as an amplifier, and also in allowing a 

 little more working distance between the objective 

 and the object itself. Having said thus much, it 

 therefore remains for each interested reader to try 

 the experiment for himself, and by using his various 

 powers (changing the oculars may also be tried), 

 by this means arrive at the best result to please 

 himself or suit his own particular purpose. I am 

 inclined to think that nothing lower than the 

 i-inch will succeed, though no doubt much will 

 depend upon the performance of the objectives 

 themselves. 



To use this erector experimentally, the instru- 

 ment must be placed in a vertical position, to insure 

 the objective remaining balanced uptm the top of 

 the ocular ; but if found suitable and intended to be 



adopted, an adapter may easily be made and fitted 

 by almost any optician in any town, one end being 

 made with the Society's universal screw for the 

 objective to screw into, and at the other end a plain 

 tube to fit on the ocular in place of the usual cap. 

 I must confess that this erector has one disadvan- 

 tage, viz., that, owing to its amplifying power, it 

 increases the defects of both objective and ocular 

 if any exist, in a far higher degree than a high 

 ocular increases the defects of an objective; but as 

 I merely suggest its use for dissecting, mounting, 

 or general manipulation, and not .for original 

 research, this failing, 'if it amounts to anything, 

 is. not of much importance. 



In vol. vi. of the Monthly Microscopical Journal, 

 page 46, I note the mention of an "achromatic 

 erecting eye-piece," but having never seen one, or 

 read even the description of one, I have no idea 

 how they are constructed ; and on looking through 

 vol. V. of the same journal, I see (page 11) that 

 Mr. S. J. Mclntyre has used a linch and Ig-inch 

 object-glass between the objective and the ocular 

 as a "searcher," — much, 1 presume, on the same 

 principle that Dr. Pigott's "aplanatic searcher" is 

 applied ; but I am quite ignorant whether either of 

 their " searchers " gives an erect image or not. The 

 employment of an objective as an erector in the way 

 I have endeavoured to describe is quite an original 

 and rather old idea of my own, but as nine-tenths of 

 my time is passed upon the ocean, I am almost 

 entirely shut out from knowing what is going on 

 in the world of microscropic science, until I arrive 

 home, and get my Monthly Microscopic Journal, 

 SciENCE-Gossii', &c., and then I have sometimes 

 found that some of my ideas have been already 

 anticipated. 



Apropos of the ocean, I often think how entranced 

 some of our "real" microscopists would be if they 

 could only spend a week or two on board a ship in 

 a calm tropical sea; the boundless treasures of 

 exquisite marine forms of microsciopic life found 

 there, I really believe, surpass anything that can 

 be imagined. The towing-net cannot be used for 

 ten minutes, or even a bucketful of salt water drawn 

 up, but it contains sufficient animal life to require 

 at least a week to work out, and such forms as, I 

 am sure, many of them, have never been figured 

 or described. After having observed them under 

 the instrument, the " thing of beauty " persistently 

 refuses to " become a joy for ever," for I have tried 

 nearly every known preservative to mount the ob- 

 ject, but have never yet succeeded. A short time 

 ago 1 caught two of those very beautiful forms, 

 the Porpita {Acalepha, order Cirrhigrada, Por- 

 pita gigantea). Being desirous to preserve their 

 very beautiful tentaculse perfect, and also to keep 

 their magnificent colour, I poured from time to time 

 a drop of alcohol into the water in which they were 

 (as recommended to kill the zoophytes with tentacles 



