. TRANSACTIONS OF THE SECTIONS. 19 
usual, though possibly owing to the hills we are now close to, and which are new 
features in our landscape. 
« Monday, Feb. 14. Barroon, East bank of Soane River, 9 p.m. Barom. 29°924 ; 
Atmos. temp. 58 ; Temp. air 62; Wet-bulb 51°5; Grass 53. Blue sky and clear 
horizon ; moon and stars clear; milky way invisible ; zodiacal light invisible ; moon 
by photometer 3°07 inches (sun at 3 p.m. being 4°17 inches). 
“Observed the auroral arch well defined, 12° broad ; alt. of upper limb (best de- 
fined) 20°. Extremes bearing W. 20 S. and N. 50 E. Light, pale but bright, rest- 
ing on an arch no darker than sky at zenith. Beams crowded, from 20 to 30 
linear and lancet-shaped, crossing the zenith and converging in opposite horizon 
towards S.15 E. All beams bright, clear and well-defined, moving slowly, forked 
at the apices or split from apex to zenith, almost obscuring stars of first magnitude. 
Longest beams point to S. 10 E. descending to 25° alt. Middle beam broad, crosses 
zenith, points S. 50 E. and descends to 40°. N.W. beams almost parallel to 
horizon, point 8. 70 E. and descend to 20°. 
“10 p.m. General appearance more diffused, upper limb of arch less defined. No 
beams cross the zenith. Two detached ones 15° above horizon at 8.15 E.; aftera 
few minutes one beam reappeared on zenith. 
«10"15™. Appearance to W. of N.as before. One beam on zenith, two cross the 
meridian, one to S. 30 E. at 15° above horizon, which disappears towards the arch 
in S.E. Arch more diffused and descending to horizon, forming a pale mass, alt. 25°. 
Beams broader, shifting ‘and splitting more frequently. Soon a dark horizontal 
band 4° broad crosses the arch, extending from N. 55 W. to N. 10 W.; upper 
limb 12° alt. ; it appears as a break in the auroral arch. Whole horizon all round 
' covered with a pale diffused light, strongest towards arch and in opposite quarter. 
Beams still clear, the lateral broadest and best defined. Dark band becomes broader, 
breaking up the arch. 
*©10430™. Beams from arch still clear, linear 2° to 6° broad, about 12 in number; . 
none reach the zenith; a few lateral ones cross the moon’s meridian, the upper 
approaching within 8° of her orb, and still well-defined. N.E. beams most crowded ; 
N.W. best defined and broadest. Dark band broader, severing the arch. Whole 
phenomena fading: longest and brightest and most numerous beams stretching 
along N.E. horizon. 
10" 50™. Still fading. Beams and arch all disappear to W. of N. 18 narrow 
beams between N. and N. 20 E. from remains of arch. Cold southerly breeze 
sprung up. 
“10% 55™. Breaking up as before. 
“11 p.m. Diffused light over all horizon (possibly reflexion of moon’s light on 
ground mist, which however is not discernible). Scattered beams like cirrhus here 
and there; linear along N. and N.E. horizon. 
«Midnight. Two faint beams to N.E., and two strongly-defined lance-shaped 
parallel ones to S.W.” 
On a General Law of Electrical Discharge. 
By Sir W. Snow Harnis, F.B.S. 
: 
An interesting discussion having arisen, at the last Meeting of the Association at 
Oxford, relative to the laws and nature of the attractive force between two conduct- 
ing spheres electrically charged, the author was led to undertake certain experimental 
| investigations with a view of verifying the application of a series by Professor W. 
Thomson, of Glasgow, (relative to this interesting physical question) who, by a pe- 
culiarly striking and very elegant method, had associated such forces with the 
principle of optical reflexions, conceiving that in the common case of electrical at- 
traction between two conducting spheres, certain electrical reflexions or images of 
force, as it were, may be conceived to be continually reflected between the bodies in 
infinitum, and that, by a particular series which he had deduced for such forms of 
action, the problem might be completely brought under the dominion of analysis. 
| The object of the present paper was to determine principally the relative degree of 
| force between two conducting spheres at the instant of discharge, and to compare 
| that with the quantity of electricity requisite to produce the discharge at given dis 
| stances taken between the nearest points of the spheres. 
; ‘ c2 
