214 SIR HERBERT JA'CKSON 



make possible the large amount of expsrimental work which, is needed 

 and which of necessity cannot be made to pay except indirectly, and 

 in the course of time. Unless we can get experiments of that kind 

 made by the people in the factories, the hoped-for advances from 

 the instrumental side will not be fulfilled, at least to the extent which 

 some of us think and believe to be possible. 



I turn for the moment to the point of view of education. The 

 growing use of scientific instruments in industry definitely calls for 

 some systematic education in the theory of them and in their prac- 

 tice. There has recently been created a School of Technical Optics 

 under the Directorship of my friend Professor Cheshire. We may 

 therefore look confidently to having opportunities afforded for a 

 thorouo-h and systematic education, now so much needed, in the 

 subject of the microscope and its use. That need existed over 25 

 years ago, but I do not know that any marked efforts have been made 

 to give the systematic education required. Take the difference 

 between the subject of spectroscopy and microscopy. In spectroscopy 

 the work of educating the student is carried out in a systematic 

 way. There is lecture work and laboratory work, and I think the 

 student of spectroscopy knows his instrument and his subject as well 

 as it is possible to do in the time he is required to spend on it. It 

 is difficult to believe that the student of microscopy ever had a 

 chance of knowing his subject so systematically and thoroughly. 

 Therefore I plead very strongly for the greatest possible support 

 for Professor Cheshire, so that he may bring this question of educa- 

 tion in the microscope to a really practical and successful issue. Of 

 the many possible forms of propaganda, none is likely to have a 

 better or more lasting influence in the direction of arousing interest 

 in the subject and extending the use of the instrument. How 

 many of us have seen people who begin with the microscope and 

 abandon it very soon after taking to it, and in nearly all cases it 

 A3LS been due to this, that they have had nobody to show them how 

 to use the instrument or to make them understand what the micro- 

 scope is, what it is in theory and in practice, and they have often 

 not been able to interpret what they see. 



We have listened to an Address by Mr. Barnard which is very 

 interesting to me, because I have had the opportunity of seeing his 

 work, and I think he is to be congratulated on the scientific work 

 he has done in extending the u?e of the microscope. But it is more 

 than that, Mr. Barnard has that spirit of research and that spirit 

 also of rcali'^ing that there is to be interpreted in the microscope a 

 groat deal that has escaped observation, although it may have been 

 seen dozens and even thousands of times. What T want to see is, in 

 addition to the necessary lectures on the theory, the formation of 

 classes in the use of the microscope where objects are studied at low 

 powers and low numerical apertures, and at high powers and high 

 numerical apertures, by transmitted light, on a black ground, and 

 by opaque illumination ; and each appearance critically examined 

 and described. 



There is a definite lesson as to how each type of image is to be 

 interpreted. May I take one or two instances. If a well-known- 

 diatom, picnrnxit/nia (UK/iildf utn , is examiued with an illuminating- 

 cone of not more than .3 to .4 N A , and with a lens like a 1 inch. 



