lS'2 THE PKESIDEXl's ADDRESS. 



papers on diatom structure, and has thus added to our knowledge 

 not only of the morphology of these interesting organisms, but 

 of the methods by which their structure can most profitably ])e 

 investigated. To Mr. Nelson the discovery of new methods for 

 the interpretation of microscopical detail is a constant and an 

 engrossing study, and I am sure that those who, in common 

 with myself, have been allowed the privilege of witnessing his 

 methods of work, will agree with me in admiration of his untiring 

 devotion to that branch of science of which he is so accomplished 

 a master. 



Mr. Nelson has also contributed to our Journal part 2 of his 

 essay, undertaken at the special request of the Council, on the 

 evolution of the microscope, which brings down the history of 

 that instrument to the year 1 744. When completed, this will 

 form one of the most interesting essays that have hitherto been 

 communicated to the Club. A very useful and thoroughly practical 

 paper is that contributed by Mr. Rousselet on " Micro-Cements " : 

 coming from a gentleman so thoroughly versed in the mounting 

 of a peculiarly refractory class of organisms, this paper will 

 be read with interest by those whose studies lie in a similar 

 direction. Several other papers and " notes " have been con- 

 tributed to the Club during the year, and full descriptions of 

 them will be found in the Journal. 



The question of " brass and glass," as we term it, is always a 

 popular one with the Club^ and, according to precedent, 1 beg 

 leave to offer a few i-emarks upon it. 



We hear a great deal nowadays about a very common type 

 of instrument to which the title ^'student's microscope" has been 

 accorded, with more liberality than justice, as it seems to me. 

 The instrument of the class to which this name has been given, 

 consists invariably of a small stand, approximating more or less 

 closely to the Continental model, with a short tube, of small 

 diameter, a stage inconveniently near the table, and where 

 a condenser is included, this is generally of the so-called Abb6 

 chromatic form, which is either made to slide in a rigid fitting or 

 is supported on a modified form of sub-stage. 



The ingenuity which has been expended on this type of stand 

 is remarkable ; most, though not all, of our English firms having 

 competed with one another to produce the most attractive instru- 

 ment at a given price. But if the type itself is not everything 



