164 
NA Tiree 
| Dec. 14, 1882 
substantially with those which have been already given for the 
months of February and August, in the wind and current charts 
published by the Hydrographic Department of the Admiralty ; 
but as the present series is founded on a much larger number of 
observations than have ever before been available for a similar 
purpose, it may fairly be regarded as a valuable contribution to a 
not unimportant part of terrestrial physics. Between the limits 
of 50° north and 50° south latitude, the mean annual surface 
temperature, so far as it can be deduced from the data now 
available, appears to be 74°°9 F. for the Indian, 69°°5 F. for the 
Atlantic, and 68°°6 F. for the Pacific Ocean. The North 
Atlantic is 4°°6 F. warmer than the South Atlantic Ocean ; the 
corresponding difference in the case of the Pacific Ocean is only 
TecSebs 
Among other contributions to Ocean Meteorology, which the 
past year has produced, I may mention (1) the Physical Charts 
of the Atlantic Ocean, published by the Deutsche Seewarte, at 
Hamburg ; (2) the second volume of the narrative of the voyage 
of H.M.S. Challenger, containing the magnetical and meteoro- 
logical observations ; and (3) a report by Captain Toynbee, 
F.R.A.S., on the Gaies of the Ocean District adjacent to the 
Cape of Good Hope, which completes the discussion by the 
Meteorological Council of the meteorology of that tempestuous 
part of the sea. 
The meteorology of our own country has been actively studied 
during the year. The Scottish Meteorological Society have 
given in their Journal a series of monthly pressure charts for the 
British Isles, together with a revised edition of the temperature 
charts already published by them in 1871. The charts now 
embody the results of observations extending over a period of 
twenty-four years; the revised edition, as well as the original 
publication, are due to the indefatigable activity of Mr. 
Alexander Buchan, F.R.S.E., the Secretary of the Scottish 
Meteorological Society. An atlas of convenient size, intended 
for the use of observers in the United Kingdom, and conveying 
similar information derived from data partly different, and quite 
independently discus-ed, has heen already prepared by the 
Meteorological Office, and will immediately appear. 
It is a fact now universally recognised that the greater part of 
the changes of weather which are experienced in the British Isles 
are occasioned by travelling areas of excessive or defective 
atmospherie pressure, which arrive at our shores from the 
Atlantic Ocean. The importance of a systematic study of the 
weather of the North Atlantic being thus indicated, the Meteoro- 
logical Council have resolved to undertake the preparation of 
synoptic weather charts for the thirteen months beginning Ist 
August, 1882, and ending 31st August, 1883, and have issued a 
special appeal to the British shipping interest for active co- 
operation during that period. It is satisfactory to know that this 
appeal has not been fruitless, and that there is every prospect 
that the number of observations available for the discussion will 
exceed 200 per day. 
This is, perhaps, the proper place to make mention of some 
results having an important bearing on meteorology, obtained hy 
Prof, Tyndall in the course of a larger research on the action of 
radiant heat on gases. 
By methods which he has applied to gases and vapours 
generally, Tyndall has established anew the action of aqueous 
vapour upon radiant heat, and the sensibly perfect diathermancy 
of dry atmospheric air. The phenomena of solar and terrestrial 
radiation are profoundly modified by the presence of aqueous 
vapour in the earth’s atmosphere, the temperature of our planet 
being thereby rendered very different from what it would 
otherwise be. 
The celebrated experiments of Patrick Wilson, wherein were 
observed a rapidity of radiation and a refrigeration of the 
earth’s surface previously unknown, are explained by the fact 
that when they were made, the amount of aquecus vapour in the 
air was infinitesimal, the unhindered outflow of heat towards 
space beng correspondingly great. The sagacious observation of 
Six and Wells, that the difference between the surface tempera- 
ture and that of the air a few feet above the surface, on equally 
serene nights, is greatest in cold weather, is explained by the 
fact that, when the temperature is low, the agent which arrests 
the surface radiation is diminished in quantity. Wells, more- 
over, found that the heaviest dews were deposited on nights 
when the difference between air temperature and surface tempera- 
ture was small; while the greatest difference between the two 
temperatures was observed on nights when the deposition of 
dew was scanty. The explanation offered by Tyndall is this :—- 
copious dew indicates abundant vapour ; and abundant vapour, 
by arresting the terrestrial rays, prevents the refrigeration 
observed indrierair, Strachey’s able discussion of observations 
made at Madras, point di-tinctly to the action of aqueous vapour 
on the radiation both of the sun and of the earth; while the 
experiments of Leslie, Hennessey, Hill, and other distinguished 
men, which were long. considered enigmatical, are readily 
explained by a reference to the varying quantities of vapour with 
which the atmosphere is charged, on days of equal optica} 
transparency. The interesting observations of Desains and 
Branley, made sia ultaneously on the Rigi and at Lucerne, are 
well worthy of mention here. The difference of level between 
the two stations is 4,756 feet, and within this stratum 17°1 per 
cent. of solar heat was proved to be absorbed. This absorption 
being due to aqueous vapour, is tantamount to the transmission 
of the sun’s rays through a layer of water of a definite thickness. 
A sifting of the rays woulda be the consequence, and on @ priori 
grounds we should iv fer that the percentage transmission through 
water at Lucerne must be greater than on the summit of the 
Rigi. This was the exact result established experimentally by 
Desains and Branley. H. Wild, the distinguished Imperial 
Astronomer cf St. Petersburg, basing his statement on experi- 
ments made by himself according to Tyndall’s method, has 
expressed the opinion ‘‘that meteorologists may, without 
hesitation, accept this new fact in their endeavours to explain 
phenomena which hitherto have remained more or less enig- 
matical.” The correctness of this statement is illustrated by the 
foregoing examples, to which, if necessary, many more might 
be added. 
At the recommendation of the Committee on Solar Physics of 
the Science and Art Department, a grant of 3507. was made from 
the Society’s Donation Fund to Captain Abney and Mr, Lockyer 
in aid of their proposed observations of the total eclipse of the 
sun at Thebes in May last. Unfortunately the state of Captain 
Abney’s health precluded his taking part in the expedition ; but 
Dr. Schuster generously undertook the conduct of his observa- 
tions, and, notwithstanding the short time remaining for 
preparation, he carried them out in the most satisfactory manner. 
Three photographs of the corona itself were obtained during 
the eclipse. They show that the corona had the characteristic 
features observed during the time of the maxima of sun-spots. 
The long streamers in the plane of the ecliptic seen during sun- 
spot minima were absent, and the corona showed much disturb- 
ance. A bright comet appeared in all the photographs at a 
distance slightly less than a solar diameter. 
A complete photograph of the spectrum of the prominences 
and the corona was for the first time obtained. The prominences: 
give a spectrum in which the lines of calcium bear a conspicuous 
part by their intensity. The ultra-violet hydrogen lines, photo- 
graphed in star spectra by Dr. Huggins, were seen, as well as a 
number of unknown lines. 
The corona gives a very complicated spectrum. Close to the 
limb of the sun the spectrum was so nearly continuous and so 
strong as to hide any lines which might have been present. 
Further away the continuous spectrum fades off, the solar group. 
G appears as an absorption line, and a large number of ccrona} 
lines hitherto unobserved appear in the ultra-violet. 
In addition to these photographs one was obtained in a camera, 
in front of whose lens a prism was placed without a collimator. 
This photograph allows us to study the spectra of different pro- 
minences. As the picture was produced on one of Captain 
Abney’s infra-red plates, all the tints of the prominences ranging 
from the ultra-red to the ultra-violet made their impressions, 
and some interesting differences in the spectra of different pro- 
minences can be noticed. 
But, beside taking part in this expedition, Mr. Lockyer has. 
continued with unwearied perseverance his observations on the 
spectra of solar prominences and spots, and has recently com- 
bined with these the results obtained by him during the late 
eclipse. During this eclipse he made naked eye observations, 
which he considers to be of a crucial character between the two 
rival hypotheses regarding the nature of the sun’s atmosphere. 
The results of this investigation have in his opinion considerably 
strengthened the views which he first put forward in 1873 on the 
constitution of the solar atmosphere. A statement of these views 
will be found in a paper by him recently resd before the Society. 
In the present state of the que-tions there raised, it must I think 
be admitted that, after giving all due weight to the facts and 
reasonings adduced by Mr. Lockyer, additional and varied 
observations are greatly to be desired ; and that no opportunity 
