1878 .] 
Scientific Notes . 285 
the microscope. We are also by no means limited to visible tints. The 
crystal may have such a powerful double refraction, or be so thick as to give 
apparently white light, and yet, by using the thicker end of the quartz wedge, 
the tints may be reduced down to those easily distinguished. This simple 
arrangement secures all the advantages of an unmanageably large number of 
selenite plates, and all necessary observations can be made v/ith ease and 
expedition. 
A valuable paper on the “Application of the Micro-SpeCtroscope to the 
Study of Evergreens ” was read before the Royal Microscopical Society 
(November 7th, 1877), by Thomas Palmer, B.Sc. As it would be impossible 
to give an abstract that would be of any use to the student, and, moreover, the 
reproduction of Mr. Palmer’s speCtrum charts would be required, reference is 
made to the original paper. 
Owing to the death of Dr. Henry Lawson, F.R.M.S., and Assistant- Physi- 
cian and LeCturer on Physiology at St. Mary’s Hospital, and formerly editor 
of the “ Monthly Microscopical Journal,” that publication will be discon- 
tinued. The “ Transactions of the Royal Microscopical Society ” will for 
the future be issued by themselves, after the manner of the larger societies. 
A mode of examining water microscopically has been contrived by W. L. 
Scott, Public Analyst to the County of Glamorgan and Borough of Hanley. 
The chief point in the process consists in the manner of filtering the water, 
by which the organisms contained in a large quantity of material are retained 
on a very small portion of the filter-paper. The centre of the filter is ren- 
dered impervious by means of a fatty composition, and the texture of the 
paper rendered more obstructive to the passage of minute organisms by being 
dipped in a very thin structureless collodion. The process is described in 
detail in the “ Monthly Microscopical Journal ” (vol. xviii., p. 239). 
In the obituary notices of the Royal Microscopical Society we remark the 
death of Mr. J. L. Denman. Although not distinguished for any published 
work in the department of minute structure, he has done that which will 
endear his memory to every analyst. An honest tradesman, disgusted with 
the adulteration practised — and unfortunately approved of by the public — in 
the article in which he dealt, he devoted much time and expended considerable 
capital in obtaining pure wine. Failing to obtain it from the usual sources, 
he sought it in other countries, and, in spite of popular prejudice, imported 
the unadulterated wines of Greece and Hungary. Just before his death he 
had the satisfaction of introducing pure wine from Spain — a country which, 
like Portugal, had always prepared its exports to the vitiated taste of the 
British consumer. His definition of wine was simpty “fermented grape- 
juice,” in old times coupled with bread as a necessary of life. 
The Telephone continues to engage the attention of physicists. A very 
complete and concise description of the construction and aCtion of the instru- 
ments of Reiss, Yeates, Gray, Edison, and Bell is contained in the report of a 
LeCture by Prof. Barrett, of the Royal College of Science, Dublin, and pub- 
lished by Mr. Yeates, of King Street, Covent Garden. 
In a paper “ On some Physical Points connected with the Telephone,” read 
before the Physical Society, Mr. W. H. Preece has pointed out that this in- 
strument may be employed both as a source of a new kind of current and as 
the deteCtor of currents which are incapable of influencing the galvanometer. 
It shows that the form and duration of Faraday’s magneto-eleCtric currents 
are dependent on the rate and duration of motion of the lines of force pro- 
ducing them, and that the currents produced by the alteration of a magnetic 
field vary in strength with the rate of alteration of that field ; and further, 
that the infinitely small and possibly only molecular movement of the iron 
plate is sufficient to occasion the requisite motion of the lines of force. He 
also pointed out that the telephone 'explodes the notion that iron takes time 
to be magnetised and de-magnetised. The instrument forms an excellent 
deteCtor in a Wheatstone bridge for testing short lengths of wire, and con- 
densers can be adjusted by its means with great accuracy. M. Niaudet has 
shown, by employing a doubly wound coil, that it can be used to detect cur- 
