( ) 
Just pahlished, post-free for Six Stamps. 
W. WESLEY & SON’S Natural History and Scientific Book Circular ; 
No. 93 (Eighteenth year of Publication), containing over 1400 valuable and important works on — 
MICROSCOPIC ZOOLOGY, | ENTOMOLOGY, 
CONCHOLOGY ; 
Forming a Portion of the S tock of — 
W. WESLEY & SON, Scientific Booksellers and Publishers, 
28 , Essex Street, Strand, London. 
FO"WEXjI-. -A-IsTID I_,E.A.Il,-A.3Sr3D, 
170, EUSTON RCAD, LONDON, N.W. 
MANUFACTURERS OF MICROSCOPE STANDS, OBJECT-GLASSES, CONDENSERS, ie. 
New Homogeneous Immersion Objectives. 
in. N.A. 1-28 .. .. £8. N.A. 1-27 .. .. £12. in* 1 * 26 .. .. £15. 
Correction Collar to either of the above, £1 10s. extra. 
APOCHROMATIC HOMOGENEOUS IMMfRSION OBJECT-GLASSES. 
i in- ) I 
-Jfj .. >1*40 Numerical Aperture, each £25 0 0 Set of 3 Compensating Eye-pieces .. £6 10 0 
ra >» ) 
Dry Achromatic Condenser £8 8 0 
Oil-immersion Chromatic Condenser £2 0 0 
Oil-immersion Achromatic Condenser £1200 
Catalogues free on application. 
ROYAL MICROSCOPICAL SOCIETY. 
MEETINGS POE 1890, at 8 p.m. 
Wednesday, January . , . . 8 
„ February . . . . 12 
{Annual Meeting for Election of 
Officers and Council.) 
„ March . . . . 19 
„ April 16 
Wednesday, 
May . . 
.. 21 
}> 
June . . 
.. 18 
» 
October 
. . 15 
5J 
November . . 
.. 19 
5> 
December . . 
.. 17 
Fellows intending to exhibit any Instruments, Objects, &c., or to bring 
forward any Communication at the Ordinary Meetings, will much facilitate 
the arrangement of the business thereat if they will inform the Secretaries of 
their intention two clear days at least before the Meeting. 
Authors of Papers printed in the Transactions are entitled to 20 copies 
of their communications gratis. Extra copies can be had at the price of 
10s. 6d. per half-sheet of 8 pages, or less, including cover, for a minimum 
number of 50 copies, and 6s. per 100 jilates, if plain. Prepayment by 
P.0.0, is requested. 
