Cock, &c. ]xi 
about to pass, through the zenith, it is generally easy to determine very nearly the 
vanishing point of the motion of any portion of cloud, by watching its progress for a 
short period; there can be no hesitation in saying, that the motions of the upper 
currents of air thus observed, are better determined than the motion of the lower 
or surface current observed from the vane. The directions of motion of the clouds 
in three strata (scud, including cumuli; cirro-stratus, including cirro-cumuli; and 
cirri), are given in numbers of points of the compass, reckoning N = 0, E = 8, 
S=16,W=24. The nomenclature adopted is that of Mr Howarp, with certain 
combinations, which are, in general, sufficiently descriptive. 
104. Full sunshine is indicated in the column of meteorological remarks by the 
symbol © ; when the sun shone through a cloud so as to project a distinct shadow, 
it is indicated by the symbol © ; when the cloud was very thin, this is indicated 
occasionally by the symbol © ; and when the sun’s disc only was visible, the symbol 
@ is used; similar symbols are used for the moon. The heaviness of the rain fall- 
ing at the time of observation has been estimated, and is noted in the column of 
meteorological remarks, upon the supposition that the heaviest fall is 10: thus, 
rain’, is rather heavy rain ; rain’, is the heaviest observed in 1844; rain, is just 
perceptible ; and rain”, is a light, spitting, Scotch mist. 
Crock, &c. 
105. The mean time clock is by DENT of London; it is kept at Gottingen mean 
time by comparisons with the transit clocks in the Astronomical Observatory, the 
errors of which are determined by Sir THomAs BrisBane, by myself, or by Mr 
Wetsu. The rate of the clock is kept small. 
106. A fire-place was formed in the space marked F (Plate I.), in October 
1845, the east anteroom being employed afterwards as a computing room; the 
chimney was formed of fire-brick tubing (which it was found could not appreciably 
affect the positions of the magnets), the grate and fire~drons were of copper. 
DESCRIPTION OF THE TABLES OF OBSERVATIONS. 
107. Hourly and Daily Observations of Magnetometers, 1845 and 1846, pages 
1-68 and 288-323. 
The first column contains the Gottingen mean solar time, astronomical reckon- 
ing, of the observations of the declination magnetometer. Gottingen time is 49™ 50* 
in advance of Makerstoun time. The second column gives the absolute westerly 
declination in degrees, minutes, and decimals of a minute, deduced as described, 
No. 17. 
The third column contains the observations of the bifilar magnetometer in scale 
divisions, corrected for temperature to 26° Fahr. (see Nos. 69 and 73) ; increasing 
numbers indicate increasing force. The bifilar is observed 2” after the declination. 
MAG. AND MET. OBS. 1845 AND 1846. 7] 
