C>F THE M!<j;osr oi>. ill) 



The study of the diatoms, in so far as their structure is con- 

 cerned, confessedly requires microscopes and objectives of the 

 very highest class. And yet we have been told by a gentleman, 

 whose name deservedly stands very high in connection with the 

 study of these interesting objects, that for the determination of 

 species, and for most other points which he has studied, he has 

 used a good non-adjusting quarter, on a simple stand, and that 

 it is but seldom that he has recourse to better objectives, of 

 which, however, he has a full series by the most eminent 

 makers. 



By the term " ordinary work," then, we may very properly 

 designate all such examinations as lead us over ground that is 

 well known, while no work that involves the examination of 

 unfamiliar structures or the investigation of unknown processes, 

 can be so called. But of all the work that is done with the mi- 

 croscope, four-fifths (including the work of the physician) is 

 "ordinary work." 



To those, therefore, who have abundant means at their 

 command, we would by all means recommend the pur- 

 chase of two microscopes always, of course, getting the cheap 

 one first. If, during the course of their " apprenticeship," this 

 cheap instrument should get injured, the loss will not be very 

 great, and by the time the student has learned to use the cheap 

 instrument, he will have acquired intelligent views as to his 

 special needs in the matter of a more complete one, and will 

 not be dependent upon the advice of any one. 



To those who cannot afford two microscopes, we would 

 strongly recommend as a stand, one of the New American 

 Models, previously described. If we except a few special de- 

 partments, such as goniometry, etc., these stands are equal to 

 all demands, and will do justice to any objectives or accessories, 

 while at the same time they are sufficiently compact and handy 

 to allow of the convenient and rapid accomplishment of all 

 kinds of simple work. 



To those who cannot afford one of these stands, the only 

 advice we can offer is to get the best they can for the amount of 

 money they have to spend. 



It would be impossible to give anything like a list of special 

 cases in which the different styles of microscopes prove most 



