1885-86.] Edinburgh Naturalists' Field Club. 329 



front — two of the most important improvements in object-glass 

 construction. 



Our English microscopes are usually sold with a 1-inch and a ^- 

 inch object-glass. Where expense will not admit of a purchaser 

 buying more glasses, these are generally sufficient to show every- 

 thing which a microscopist wishes to see, except fine tests ; but 

 both a lower power and a higher one are desirable. When a lower 

 power is desired, one of 2 inches focus should be got ; and for a 

 higher, a water-immersion of about — of an inch focus. English 

 low powers by the leading makers are unrivalled. Continental 

 makers, as a rule, do not make good low powers — the very powers 

 with which the most of microscopic work is done. I, of course, 

 except Dr Zeiss from this statement, as his glasses, from the 1- 

 inch upwards, are unrivalled. Foreign microscopes generally 

 have a considerably higher power than a ^ of an inch glass for the 

 high power, and this is certainly an advantage they possess over 

 our English quarter. English opticians have devoted far too much 

 attention to the perfection of the brass work of the instrument, and 

 not enough to the optical part. At the present time, however, we 

 have one English optician whose work in the higher powers has 

 not yet been equalled — viz., Mr Hugh Powell. 



There is no hard-and-fast rule which can be given to a purchaser 

 of a microscope. Experience must be one's only guide — either 

 one's own or that of a friend. Buying a microscope depends very 

 much upon what one is able to give. But there is one advice 

 which every one ought to follow, which is. Whatever you buy, buy 

 something good. If object-glasses, get one good one to begin with, 

 rather than two bad cheap ones. Microscopes never can be very 

 cheap if good ; but it is much better to build a good one up by 

 degrees, as it can be afforded, than to buy what after-experience 

 will show you is unable to give you satisfaction. At the present 

 day I should say that every article made by Dr Zeiss may 

 thoroughly be depended upon : the stand is good, the glasses are 

 good, and the prices are reasonable. 



At the same meeting Mr Allan exhibited and described a slide 

 showing the fructification of Delesseria alata — an Alga which he 

 found on the shore between North Berwick and Tantallon Castle, 

 when the Club visited that place last summer. The fruit, which 

 was in the form of tetraspores imbedded in the margins of the 

 leaflets, was in fine condition ; and the slide was of interest from 

 the fact that this Alga is rarely found in fruit. He also exhib- 

 ited several other slides of Alga^ in various forms of fructification. 



At the third meeting (Jan. 8, 1886), a lecture was delivered by 

 G. Sims Woodhead, M.D., F.R.C.P.E., on "The Role of Micro- 

 organisms." The lecture was of a highly interesting character, 



