TRANSACTIONS OF THE SECTIONS. 381 
On the Distribution of Fog round the Coasts of the British Islands. 
By Dr. Guavstonz, F.RS. 
Certain conclusions on this subject formerly arrived at by the author had been 
re-examined by means of additional returns from the meteorological journals kept 
at all the stations belonging to the three general lighthouse authorities in England, 
Scotland, and Ireland, and some returns lent him by Mr. James Glaisher. These 
afforded confirmation of the greater uniformity of distribution of fogs over the 
surface of the sea than on land, of their great prevalency where the south-west 
wind from the ocean strikes upon high ground, of the comparative infrequency of 
foe on the coasts of straits or portions of sea nearly surrounded by land, and other 
oints previously noted. The returns also indicated that some years are much more 
oggy than others in nearly all localities; that the same fog sometimes prevails 
over a large extent of country; and that the frequency of fog differs very greatly 
in different months of the year, January, February, or March being on some coasts 
almost free. A generally accepted means of distinguishing between “fog” and 
“mist” is a great desideratum. 
On a New Barometer used in the last Balloon Ascents. 
By J. Guatsumr, F.R.S, 
Mr. Glaisher exhibited a mercurial barometer which had been designed and con- 
structed by Messrs. Negretti and Zambra for the purpose of checking the readings 
of the Gay-Lussac’s barometer which had been used in the several late balloon 
ascents. ‘The correctness of the readings of a Gay-Lussac’s barometer at low 
pressure depended upon the evenness of the tube, and it is difficult to calibrate so 
large a tube. Messrs. Negretti and Zambra selected a good tube, 6 feet in length, 
attaching a cistern to its lower end. Mercury was boiled throughout the length of 
the tube; at the entrance of the cistern was placed a stopcock, by which means 
any definite quantity of mercury could be allowed to pass from the upper half of 
the tube into the cistern, and its height in the cistern noted and engraved; then a 
second portion, and so on. This process could be repeated. When the cistern 
was thus satisfactorily divided, the tube was cut in two, and to the upper half the 
cistern was joined ; a scale was attached to this portion, and the reverse operation 
was performed, viz., allowing portions of the mercury to pass from the cistern 
into the tube, which could be regulated by means of the stopcock, and thus the 
scale was divided. The process, in fact, is using the tube to graduate itself. In 
carriage, the stopcock locks the mercury in the tube. This instrument was used, 
and acted well on the extreme high ascent. 
On the Additional Evidence of the Indirect Influence of the Moon over the 
Temperature of the Air, resulting from the Tabulation of Observations taken 
at Greenwich rn 1861-62. By J. Park Harrison, M.A. 
The author stated that the additional evidence derived from the observations of 
mean temperature at Greenwich for the years 1861-62 confirmed the conclusions 
arrived at from a tabulation of the observations for the forty-seven years previous, 
viz., that the temperature of the air at the moon’s first quarter is higher than it is 
at full moon and last quarter, and that this is due to the amount of cloud at first 
quarter being greater on the average than it is at the periods of full moon and last 
quarter. The difference in the amount of rain also at first quarter in 1861-62 was 
2-27 inches more than at full moon, on a mean of eighty-four observations on seven 
days at each period. 
On the Relative Amount of Sunshine falling on the Torrid Zone of the Earth. 
By Professor Hunnussy, F.R.S. 
By the aid of the author's transformations of formule given by Poisson, the area 
of that portion of the equatorial regions of the earth which receives as much sun- 
shine as the rest of the earth’s surface is ascertained. This area, at the outer limits 
of the earth’s atmosphere, is thus found to be bounded by parallels situate at distances 
of 23° 44’ 40” at each side of the equator; hence the amount of sunshine falling on 
