SCIENTIFIC SUMMAIiY. 
50 
c%- 
O 
ASTRONOMY. 
Transit of Venus . — In a letter to Sir R. Murchison, Professor Airy recom- 
mends, as a point well worthy of the attention of the Geographical Society, 
and in reference to the proposed exploration of the Polar Regions, that the 
portion of the antarctic continent at which the next transit of Venus v/ill he 
2 uost favourably seen should be surveyed, in order to determine if a suitable 
station can be found, and vdiicli has the necessa.ry climate and clearness of 
sky. There is no difficulty in respect to the northern stations at which it can 
be observed (which will be on the Atlantic seaboard or at Bermuda) ; but 
unless the proper locality can be found for the southern one in the transit of 
December 6, 1882, no use can be made of this rare occurrence in determining 
the distance of the sun. The point in the southern hemisphere is situated 
about 75 degrees of West Longitude and 65 of South Latitude. The only 
inquiry which need be instituted would be to determine whether such a 
station can be met with, and where the sun can be seen at two and eight 
o’clock (Greenwich time) at such a period of the year. The proposed expe- 
dition might, of course, include other objects, as geography, geology, hydro- 
graphy, magnetism, and meteorology, and might lead to very important 
discoveries in those branches of science. 
Distance of Moon. — Mr, Stone has calculated a new value of this important 
element from a comparison of the lunar observations made at the Greemvich 
and Cape of Good Hoj^e observatories during the years 1856-1861, and which 
were taken with instruments of nearly the same optical power. He groups 
together the observations of the north and south limbs, being convinced that 
personal error exists in measuring the discs of the sun and moon. The final 
result obtained is, however, nearly identical with that lately obtained by 
Mr. H. Breen, 
Sun Spot Period . — Professor Wolf, of Zurich, has undertaken the laborious 
work of determining the number of sun spots at the different periods when 
the planets, more especially Jupiter, a,re in perihelion and aphelion. In the 
year 1859 he expressed his opinion that Jupiter determines the leading cha- 
racter of the sun-spot curve, that Saturn causes small alterations in the height 
and length of the undulations, and that the earth and Venus determine the 
indentations of the curve. More recently, Mr. Carrington and Mr. De la Rue 
have returned to the same subject, and the latter, in conjunction witJi 
Mr. Stewart, has found that when “ the sun or a part of the solar surface 
approaches a planet, the spots disappear, or the brightness increases.” It is 
the intention of Professor Wolf to calculate for every five days a mean relative 
number of sun-spots during the period 1811 — 1865. He gives the results of 
a portion of his labours in showing the connection of the sun-spot period of 
11,11 years with the revolution of Jupiter between the years 1805 and 1816. 
The numbers given are certainly veiy remarkable, for whilst only 21 spots 
were visible soon after the perihelion of Jupiter in 1809, 64 were seen in 1815 
at the time of the aphelion. The progression of the numbers is otherwise very 
remarkable. 
