MICROSCOPE. 



219 



reflector. 

 Pig. 11 



I.ifbrk- 

 hun* tin* 





 ingl* rai- 



r : 



SIn-ie Ml- of colour, is a simpler construction than that shewn in 

 cwcoprs. Fig. 7. 



.^"Y"' Following out the principles which we have here ex- 

 "" plame<l. Dr. Bivw-ter has propoied a miscro-cope, c- n- 

 glr micrcil structed as in Fig. 1 1. where AB, CD, are two double 

 cope, wiib convex lenses, so constructed that the concave lenticular 

 m inducted space ABIX'. would, when filled with a fluid of differ- 

 ent dispersive and refractive power, correct the aber- 

 ration of rcfrangihility. A convex speculum of steel or 

 polished si! rated with an aperture e/i has its an- 



terior surface Pe-Q highly poli.-hed, and e-'ther attached 

 by a transparent cement or not to the lens AH. The 

 aperture /being filled with the proper fluid, and CD ce- 

 mented to the |Hsterior pnrt of the steel, the lens is 

 ready for uie. The curvature of the reflector I' 

 such ai to reflect parallel rays incident on AB, upon 

 the object to be examined, being converted into a 

 cave speculum by the lens placed before it. 



By this means, we obtain a lens possessing very 

 ir.u-iial properties, and capable of affording the most 

 perfect view of microsci'. '. 



Having thus described the various kinds cf single 

 microscopes which have been used, we shall now give an 

 .nt of the improvements which have been made in 

 adapting them to the examination of minute ol>jrcU. 



The first and most important of these improvements 

 was made about the year IT*'.', by Or I.icberkhun. 

 lens on the centre of a convex 

 speculum, madeof silver.and highly polished, and having 



icavitv so .! length of the 



that the b^ or of the kv could be thrown 



c observer. When 



the single lens is of a small focal length, the light is 



I only by its proxi- 

 mity to the lei; the body of the observer, so 

 that it becomes imp ' examine microscopic ob- 

 partictilarry opaque ones, with any satisfaction. 

 '. .iebcrkhun adapted a microscope to every object 

 of any particular interest. At the eye end of a short 

 brass tube, he pi iced the concave speculum, carrying 

 centre. '1 he object was placed in 

 of the tube, and had a contrivance for ad- 

 jiHtiii \ision, and at the object end of the 

 . there was a plano-convex lens for concentrating 

 mcave speculum. Some 

 ;:croscopes are said to be deposited in the 

 1 ' isc-urn. 



W'c shall now proceed to describe some of the best 

 ->scoj)c as fitted op for use. The most im- 

 portant of these are : 



ommon flower and insect microscope. 

 The small microscope, with apparatus for opaque 

 obj i 



'. botanical microscope. 



4. The pocket botanical and universal microscope. 

 let's anatomical microscope. 

 ni's picket microscope. 

 :lis's aquatic microscope. 

 8 Barrel microaco 



I. Dtseiiptton oj the Common Flutter and Intect Mi- 

 crotcopt. 



This i mo-t simple, and the 



liarly fitted lor In-ing put 



he tun.N of young p- T-OIIS, who are not capable 

 of m n.'giiig . implicated apparatus. Above 



the huii'lie 11, I ;,;. IJ. is lixed the aim LM, which 



D m 



Of lot CIMB 



fnvn d>,*cr 

 MM) iiwcct 

 p. i.. 1. 1 most 

 I'L.T into t 



h, f . I 



ec't'!'' 

 ^ t 13> 



carries a lens at L, which may be either used alone, single M 

 when a small power is wanted, or in conjunction with 

 another lens a, which screws on the ring at L, when a 

 hither power is needed. A horizontal grooved arm 

 MS, al<o fixed to the handle, carries the pincers or for- 

 ceps. OP which hold the ol>j*ct O, and this object can 

 be placed at different distances from the lens 1 . ><> as to 

 obtain (ii-'n; -t \i>ion l>y ^lidine the forceps along the 

 groove in MX, and fixing it at the proper position by 

 means of the button or nut B. 



II. Dctcripiion of' the Microtcoprfor Opaque Ohj,cts. 



This microscope, which is a little more complicated Description 

 than the preceding, is represented in Fig lo. The of "'< m " 

 ivory handle I" is fixed in the arm A, through which 

 passes a screw B, having its ot-ier end f.i-tened to the 

 moveable arm C. By turning the nut 1) upon the 

 head of the screw B, the arms A and C may be either 

 separated or brought together, being kept asunder 

 by a steel spring I-'.. Trie piece (ill, c.>niting of 

 a pointed steel wire d, and of a pair of pliir^ II, 

 panel through a spring socket moving on a rivet. 

 The object may be either fixed on the point G, or 

 taken up by the pliers, and may be turned round 

 in any direction, by the joint at F, or by sliding 

 the piece (ill through the spring socket. A ring of 

 brass I with a female screw is fixed on un uprglit |>tv 

 of brass turning on a pivot, in order that it may be set 

 *t a proper distance when the sin. -nifivrs are 



employed. A concave speculum K, of polished silver, 

 has a lens placed in it> centre, according to the method 

 (it Dr. I .< lj< rkliun, already <K-nil>ed; and there are 

 generally four ot the-eof different concavities, with four 

 glasses of different magnifying powers. A round ob- 

 jei-t-plate as shewn at M, has one side white and the 

 other black, all dark objects being placed upon the 

 white side, and all light objects upon the black side, in 

 order to render them more visible by contrast. A steel 

 spring N, moving round the centre, can be turned 

 down on each side, lor the purpose of pressing the ob- 

 ject to the bUck or white ground. A hollow pipe pro- 

 ceeds from the object-plate, in order to screw it on the 

 point of the needle O. A small box O of brass, with 

 on each side, for the purpose of em-losing any 

 living object for examination, has likewise a pipe for 

 the purpose of screwing it upon the end of the needle 

 FG A pair of pliers fur taking up any object is shewn 

 at (). and a soft hair brush at li. 



In uingthis microscope, the speculum KL, with iti 

 accompanying magnifier, murt be screwed into the ring 

 I 1 he object is then to be placed according to its na- 

 ture on the needle G, in the plier H, or on the black 

 or white side of the object-plate M, or Ix-tween the glass 

 plates of the box O ; and having taken the instrument 

 by the handle P, the eye looks through the magnify- 

 ing lens screwed on at I, and by means of the nut D, 

 and the motion of the net-die, the object may be turn- 

 ed about, raised or deprived, or made to approach to, 

 or recede from the lens, till it i placed in ttie true an- 

 terior focus of the lens, where the light will be reflect- 

 ed upon it by the concave speculum. 



III. Wilkeriiif'i Botanical Microicope. 



The botanical microscope used b\ Or. Withering, is 

 ten A. P.. < . ..re three parallel brass 



plates. Two wire- ;ire rivcltrd into the up- 



per and lower plates A and C, and the middle plate B 



Wlther- 

 '"'" txw ' 



j,, 



8tt UM Mtoturj* PMImrUntJimrntt, No. V. or VoL ill. Fart I 



I 



