TRANSACTIONS OP THE SECTIONS. 
47 
period of observation exceeded that at H in the ratio of 1 \ to 1. For short periods 
of rainy weather, of from two to eleven days, the ratio deviated from this average 
value in a somewhat irregular manner, showing, however, a tendency to increase on 
the approach of winter; for periods of a calendar month the deviations from the 
wan ratio were much smaller. To throw some light on the question, whether the 
puller depth of rain-fall at G, as compared with II, was chiefly owing to the higher 
attrition of the ground, or to the greater proximity to the summits of the hills, the 
of rain-fall at these points was compared with the depth as published by Mr. 
'■imore, at the Glencorse Reservoir, on the south-past, side of the range, at a 
r : nt designated bv F, only 30 feet higher than H, but almost surrounded by the 
■ighest summits oi' the chain. Notwithstanding the lower level of F as compared 
*^G, the rain-fall at F was somewhat the greater; a fact which seems to indicate 
*k< the vicinity of high summits has a greater influence ttmn mere elevation. The 
ptpngs of the flow of the streams bv Mr- Heardmore near F, and by the author 
■'■'V f«, show that the rain-fall nearer the .summits than these points must have 
greater still. The rain-fall at H exceeded that at a point in the immediate 
Vicinity of Edinburgh, 230 feet above the sea, in the ratio of I to 1 * 26 . 
On Aurora Borea/es observed at St. Ives . By J. King Watts. 
On 
Instruments. 
“» fasy Method of making thin Glass Cells for mounting Microscopic 
Objects in Fluid. Ihj C. Brooke, M.A ., F.li.S. 
ftttifn. 'Jffbihty of thin glass cells, compared with cells consisting of a r ‘ tl S 0 ^ 
1 ,imvl l Varni ? .‘ laiJ 0,1 the slide by a brush, is well known to microscopists; but 
IV *» Ul -J lcrtf > somewhat difficult uf construction, and therefore expensive, 
'•♦t*,*,, w, wode of mnkiug them consists in clamping the, piecc^ uf t[lc 
pieces are 
two steadying-pins. One 
has a narrow raised rim. 
. de 01 making them consists in ckunping the piece or nuu 
L :, --s A lms ° r gun-mctul, having each a cylindrical hole, but one o 
: '"pcd bv .u ° r °' 05 im ' h ^rger in diameter tlmn the other, llw 
-f tl '" "nn'r,«n,i° SCr 5 Ws ’ t . lle ' lu,es being kept concentric by 
•'uto'iin-,, s ?f aces is gl’Ound very flat, and the other - — 
»“On and u „ f de ' Cuverctl with very thin leather surrounding the hole, to tusure 
: "' 1 ' ft ides of tl ° rm l ,rcssure Hound the intended aperture. After scratching™ 
;i ' Cl u >ttybI^ C i, 8 , ass rcvealf tJ l, y “ic 1‘oles with a writing diamond, the circular 
pushed out without any risk of cracking the remainder of the glass. 
' CouncuZf 1 !! 0 {^“wings of Meteorological Instruments adopted by die 
P.fi.l y t J Ule Iir d'tsh Meteorological Society. By John Lee, 
fbtse a. 
u 'ennni e ,, Ph0t ° 8ra P h:4 * taker ‘ by Mrs. Glnisher, were of the standard J 
sta ud» and l " Wot and dr y hull)' and other meteorological instruments 
^ietv 'l'i 1 ' r Q? ee , ments ’ as w«*d ‘Old recommended by the British Mjteor°lo- 
V) London* 1n i i‘ ari * Barometers arc those made by Mr. Burrow, o 
4ai “bra, , 8nd the several thermometers and their stands by Messis. Ncgre 
8 80 Bie rain-gauge constructed by Mr. Glaisbcr. 
’The s t ae(- ^ °f Manufacturing Cylindrical Lenses. By Piok Sturm. 
£f years°-!!f^ w J l ' c htlu* science of optics has passed since Ruler s discovery, 
^;, Dflhe svstfm°’f°i f the P ri «cipIoi< of achromatism, have not proved theinfal 
^lindrU f h f 8phcric “ 1 fur purposea. I now, However, call 
" ll b BUc’h nor f ta .- Ien8es ground by machinery, invented by myself, v> 
i r Section that I humbly hope they may be the means of opening 
baro- 
with 
