158 Photographic Delineation of Microscopic Objects. 



PHOTOGRAPHIC DELINEATION OF MICROSCOPIC 



OBJECTS. 



BY GEOEGE S. BEADY, M.R.C.S. 



To be able to produce with rapidity and faithfulness representa- 

 tions of such objects and phenomena as are visible in the field 

 of the microscope, is a matter of great importance to the 

 labourer in almost every branch of natural science. Some 

 observers are content to discard all adventitious aid, and to 

 draw from the microscope in the same way as they would from 

 an unniagnified object, relying for success on" their own skill 

 as draughtsmen. But though this method when well practised 

 gives results, perhaps more spirited and life-like — more artistic 

 in short — -than any mere camera drawing can do ; it is evident 

 that the skill required is greater than can be brought to bear by 

 the greater number of microscopists, and, moreover, in the best 

 case it offers no unquestionable guarantee of faithfulness. To 

 obviate these difficulties, to lighten the labour on the one hand, 

 and to ensure perfect accuracy, at least of outline, on the other, 

 the instruments in common use are the camera lucida of Wol- 

 laston and the steel disc of Sommering. These are adapted to 

 the eye-piece of the microscope, and by throwing the image 

 down on to the table, so that its outline may be easily traced on 

 a sheet of paper, they offer very great advantages. But even 

 with these appliances, when the object to be drawn is very 

 elaborate in its details, the labour involved is great, and in the 

 case of living organisms their movements are a source of great 

 perplexity, as an unlucky twitch of a limb may in a moment 

 render useless the work perhaps of hours. Photography of 

 course very early suggested itself as the remedy for all these 

 hindrances, and a very encouraging amount of success attended 

 the first attempts which were made in this direction. Mr. 

 Shadbolt, many years ago, published in the Microscopical 

 Society's Journal one or two very good photographs of micro- 

 scopic objects, with an account of the process which he adopted, 

 but it does not appear that any great practical results have 

 followed so auspicious a beginning. For a long time, indeed, 

 the cumbrousness of photographic appliances was a sufficient 

 bar to any general use of them. In the midst of microscopic 

 investigation, to have to busy oneself with preparing sensi- 

 tive plates, and going through the whole processes of exposure, 

 development, and fixing, was more than could be tolerated ; 

 but now that iodized plates can be kept always ready for use, 

 and after exposure may be left any length of time for develop- 

 ment, there is very little to be urged as to the unhandiness of 

 the process, which is indeed exceedingly simple. 



