I1o THE MICROSCOPICAL NEWS, 
seasons, the nature of the soil, &c. Several points are here dis- 
cussed, which should have the attention of all those who desire to 
study the subject: the dimensions of the dust ; the suspension of 
the dust in the middle of the air; chemical composition of the 
atmospheric dust ; dust obtained by the evaporation of atmospheric 
waters ; the examination of rain waters; dust and sediment con- 
tained in snow water. 
Part II. deals with the existence of ferrugineous and magnetic 
corpuscles in the atmosphere, and no doubt this section will be in- 
teresting to our readers, especially those who have had the 
opportunity of examining Mr. Dancer’s slides of the dust from 
boiler flues and Bessemer converters. Many figures are given by 
M. Tissandier, which are accurate representations of these slides. 
Mr. Dancer’s paper, already reproduced in abstract in these columns, 
furnishes an explanation as to how these particles get into the air, 
and shows also that their source may be purely terrestrial. 
The treatise concludes with an account of pollen rains which 
have at times caused so much consternation amongst the inhabitants 
in country districts. It is a pity that these subjects are not more 
studied by those who possess Microscopes in this country. 
This little book we recommend to our readers, as affording sub- 
ject for much thought and study, and we feel sure that any one 
purchasing it will not be disappointed. 
DIAMOND LENSES.—A correspondent writes to ask if we think 
the diamond will ever come into use again for the construction of 
the “‘ fronts ” of ordinary lenses. Perhaps this query may meet the 
eye of some practical constructor of objectives, who may be more 
likely perhaps to solve the problem than we fancy ourselves capable 
of being. 
* + * * “ * 
Apropos of the subject, Pritchard states in his ‘ Microscopic 
Cabinet,” “a diamond lens exhibits the real object without any 
sensible aberration, like that produced by single glass lenses.” 
THE MicroscopicaAL BULLETIN.—Messrs. J. W. Queen & Co., 
of the States, has sent us a copy of their Journal which has been 
issued under this name. For the diffusion of Microscopical informa- 
tion it seems to us invaluable, and for the purpose of showing the 
nature of its contents we have abstracted several of the communica- 
tions for our present number. 
AYLWARD’s COLLECTING Case.—The maker of this useful com- 
panion has now further improved it, so that it may a/ways be 
carried in the pocket without any inconvenience. The new one is 
rendered more portable than any we have seen before, remaining 
at the same time an extremely convenient size. 
