August 19, 1909] 



NA TURE 



23: 



loss of efficiency, but rather ihc contrary. The cost, too, 

 lias been greatly reduced, so that unless objectives and 

 other optical parts of the highest class are required, a 

 complete microscopic outfit may now be obtained of good 

 quality and of high efficiency for a few pounds. The 

 same, however, can scarcely be said if objectives of the 

 finest quality are required, but this is rarely necessary for 

 I iiinmercial purposes or for laboratory use unless work of 

 I liighly critical nature is to be carried out. 



In our present state of knowledge it may almost be 

 said that the science and practice of microscopic optics 

 has reached such a stage of perfection that it is difficult 

 to foretell in which direction the next improvement is to 

 be looked for, much less the means by which such may 

 be effected. Attempts have been made to increase optical 

 efficiency, particularly by various dark-ground illumina- 

 tion methods, but it must be confessed with somewhat 

 disappointing results. While such methods assist in 

 demonstrating the presence of particles or isolated objects 

 not easily seen, or even invisible by other means, the 

 resolving power of the optical system is not improved. 

 The most promising development has been in the apparatus 

 introduced by Messrs. Carl Zeiss for use with ultra-violet 

 light. This certainly held out a prospect of definite 

 increase in resolving power being obtained, and in some 

 directions has probably justified its existence. For the 

 ordinary worker, however, the great cost of the necessary 

 appliances, the more than usual skill required in its 

 manipulation, the necessity of using special mounting 

 materials, as well as the impossibility of observing any 

 object mounted in the ordinary way on glass, has pre- 

 vented its use for any but very special purposes. 



For a long time a form of microscope stand, known 

 as the Continental model, in which the instrument was 

 supported on a foot of a horseshoe shape, practically held 

 the field; but English makers, fortunately, to a large 

 e.\tent maintained their more stable method of support 

 by means of a tripod foot. The latter not only admits 

 of the microscope body being more conveniently swung, 

 hut also ensures that at any inclination of the bodv-tube 

 the centre of gravity of the instrument is well within the 

 triangle formed by the three points of support. With the 

 horseshoe foot this is not the case, as the point of support 

 is usually in such a position that at any considerable 

 inclination the instrument is unstable, while in a hori- 

 zontal position for photomicrography or projection, some 

 Continental types are so unevenly balanced that thev \\'\\\ 

 not even stand alone, much less allow of the proper use 

 of their various adjustments. This may be in part over- 

 come by clamping the instrument down to some stable 

 base for such special purposes, but no microscope with 

 any pretension to be regarded as well designed should 

 require that precaution. 



The influence of this condition is now being felt verv 

 largely, and most Continental makers are either adopting 

 a more stable method of support appro.ximating to the 

 Knglish model, or are embodying the English tvpe in 

 tlieir later makes of stands. In some cases a fusion of 

 the two types appears to have been attempted, with 

 certainly beneficial effects, but unfortunately the objections 

 to the Continental model are still to be met with in some 

 that have only in part realised the advantage of the 

 English design. Continental microscopes have also long 

 been open to the objection that their substage arrange- 

 ments are altogether too cramped, and as it is only for 

 very special purposes that a microscope is of necessity a 

 portable instrument, the reason for this is not easily seen ; 

 certainly some more space underneath the stage, a greater 

 range of action of the substage condenser, and consider- 

 ably more freedom of movement of the mirror, would 

 result in the production of a more convenient style of 

 instrument. 



It is extraordinary how widespread the applications of the 

 microscope are at the present time. A recent article on its 

 use in metallurgy and engineering, by Mr. W. Rosenhain, 

 wiiich appeared in these columns (vol. Ixxx., p. 2^0), has 

 sufficiently and clearly indicated its value in this direction. 

 It is well enough known that in trades like brewing the 

 microscope has played a very important part, and, in fact, 

 it may be said that all trades which are concerned in the 



NO. 2077, VOL. Si] 



production or use of fluids for human consumption — at 

 least where the work is carried out on anything approach- 

 ing a large scale — are now compelled to have the service 

 of a trained microscopist. Dairy workers, mineral-water 

 makers', and all authorities concerned with tjie supply of 

 pure water for drinking purposes, are equally interested 

 in the question. 



As indicative of how great is the interest in this direc- 

 tion, it mav bo mentioned that the Cunard Steamship 

 Company and the White Star Line have inquired of well- 

 known makers for instruments and complete outfits suitable 

 for their use. The presumption is that they intend to 

 initiate some method of microscopically examining the 

 water supply on their vessels, constituting, in fact, a 

 miniature \Vater Board to ensure that their water supply 

 is as free from any bacterial or similar contamination as 

 even that to be obtained in great centres of population. 



As indications of some other directions in which micro- 

 scopes are being utilised, it may be mentioned that 

 chemists and druggists, paper manufacturers, makers of 

 Portland and other cement, such as the Associated Port- 

 land Cement Company, foundrymen, printers and half-tone 

 block makers for photographic reproduction purposes, 

 quarrymen, linen, cotton, and silk manufacturers, and 

 various other allied trades, are using microscopes at the 

 present time. Petrological microscopes, in the develop- 

 ment of the design of which great improvements have been 

 made of late, are being applied now for testing stone 

 and for supplying architects with exact information as to 

 the structure and quality of the stone supplied by qijarry- 

 men, and as to the suitability of such material for building 

 purposes. 



As the result of a series of lectures given to laundry- 

 men by Prof. Herbert Jackson, of King's College, an 

 interesting further use of the microscope has recently 

 arisen. Some lai-ge laundries and dyeing and cleaning 

 establishments are now installing a microscopical outfit. 

 The result of this may be fairly widespread, as it will 

 now be possible, when a customer brings an article to 

 be cleaned or otherwise dealt wnth, to determine its e.xact 

 constitution before any effort is made to carry out the 

 process. The result may be that an article which has 

 been, for example, described originally to the purchaser 

 as pure silk may at once be recognised by the laundry- 

 man as something totally different, and he may thus^ be 

 saved from manv unpleasant recriminations and possible 

 krtal claims by obtaining definite knowledge of the article 

 bclore doing any work to it. One single thread detached 

 from the article will usually supply all the information 

 required and will, in addition, often decide the best method 

 or process that can most suitably be employed to effect 

 the desired renovation. , . , , 



There is still need, however, for much educational work 

 in the use of the microscope, and it is much to be re- 

 gretted that there appears to be no institution where 

 systematic instruction in its various uses and possible 

 applications can be obtained. Even an elementary course 

 in the use of the instrument, suited to the requirements of 

 the student, would be more than useful. Medical students 

 and others who mav sooner or later engage in research 

 work are too often given the barest instruction in micro- 

 scopic technique, and it is easy to see that, could they 

 but have even a short course of instruction— which should 

 be regarded, not merely as incidental to, but as an abso- 

 lutely necessary preliminary portion of their class work 

 then' much of the rough-and-ready usage seen in the course 

 of laboratory work might be avoided. It seems almost 

 absurd that 'a student who is taking a course in bacterio- 

 logy or pathology, which at its best requires the very 

 highest knowledge of the use of the microscope, should 

 usually receive little or only the barest and most superficial 

 instruction in the methods of use of the instrument. With 

 the great increase in the number of applications of the 

 microscope, it mav become essential that means should be 

 provided for teaching systematically the elements of the 

 theory of microscopic optics and the methods of using the 

 instrument and its optical parts, and it is to be hoped that 

 at no distant time this necessity will be recognised in 

 some institutions of higher education. 



J. E. Barnard. 



