230 MEMORANDA. 
pen of Mr. C. Brookes, F.R.S.,” as printed in the Journal 
for April, 1864, it is stated that “an admirable method of 
determining the available angle of aperture of an objective 
was suggested to the jury by Professor Goyin, of Turin, &c. 
&ec.”’ Mr. Brookes apparently was not aware when he pre- 
pared that report, and many of your readers may not be so 
now, that Professor Govin’s method is precisely the same as 
that described in the Journal for July, 1859, p. 256, by Mr. 
P. Gray, 7, St. Paul’s Villas, Camden Town. Any one who 
takes the trouble to examine the matter carefully will find 
that they are alike, the only difference being in the position 
of the microscope. It is not necessary to convert the instru- 
ment into a telescope by placing a series of lenses above the 
eye-piece ; the naked eye, without any eye-piece, is far better, 
and gives a clearer sight of the edge of the strips of paper. 
I have an excellent quarter-inch glass, by A. Ross, and by 
the above method it possesses an angle of aperture of 831°. 
Mr. Gray’s quarter-inch glass had an aperture of 821°. I 
have thought it right to bring this matter before your readers, 
as Mr. Brookes ought to have been able to tell the jury that 
the method of Professor Govin was then known in England, 
—W. Forean, 3, Warriston Crescent, Edinburgh. 
Errata——In the April number of the Journal several 
printer’s errors were allowed to stand, owing to the printer 
not sending proofs. The reader is requested to make the 
following corrections : 
Page 99 of the Journal, line 6, for Axnelide, read Annelida. 
» 20, insert between ¢he and ambulacral, 
pseud-hemal and. 
», 26, for Clenophorous, read Ctenophorous. 
» 29, for Asteropods, ,, Arthropods. 
2» 3 bP] 
” 102 ” ” 28, 9 SG: 9, ” Jig. Mg 
23 108 »” ” 40, 9» ONe, 3 «=a. 
Pe ar <A omit the last five words. 
lle: x in the Bibliography, after D’Udekem read 
for Ful., Jul. 
ees Kb oe line 3, for 7sis, read Isis. 
elias) * s, 6, 5, Lewhonek, », Lenhossek. 
” ” ” ” 15, ” Mury, ” Murie. 
» 1909 aa » 2, 59 Primularia, ,, Pinnularia. 
» 140 4. » 08, 5» Lerustreminacee, read Terustro- 
miacee. 
:, A is » 4, 5, Orchiducee, », Orchidaceae. , 
5 isi cs », 22, ,, murderess, 3» «mother. 
