562 Chronicles of Science. [Oct., 
Transit Circle of the Royal Observatory, Greenwich, 1851-1865.” 
The result is as follows :— 
Supposing 6p, dc, and 6m to be the respective errors in the 
assumed values (0”°00, + 0”°08, and — 0”°03, respectively) of 
the proper motion of Polaris, 51 Cephei, and 6 Urse Minoris, in 
North Polar distance, the expression for the Nutation Constant 
comes out— 
9”-133 4+ 3°05 8p + 0-448 m — 0-90 8e. 
Mr. Proctor points out that no notice is taken in the Nautical 
Almanacs of certain partial Lunar Eclipses—those, viz., in which 
the moon passes within the earth’s penumbra, but not within the 
umbra. This seems to be a defect, because penumbral passages 
have now an evident value on account of the application of spectro- 
scopic analysis. There seems to be something defective also in the 
theory of eclipses as usually presented in works on astronomy, in 
which no notice whatever is taken of penumbral lunar eclipses. 
Mr. Proctor gives the elements of a penumbral eclipse of the moon 
which took place on the morning of September 2nd of the present 
year. 
4. BOTANY, VEGETABLE PHYSIOLOGY, AND * 
MORPHOLOGY. 
America.—Diatoms, d&c., in Hot Springs——Mr. A. M. Edwards 
draws attention in a recent paper to the occurrence of Diatomaceze 
belonging to the genera Orthosira, Fragillaria, and Cocconema, 
together with the hairs of insects, in some fine sandy deposit ob- 
tained from a Geyser. Dr. Lauder Lindsay enumerates seven 
genera of Confervee and Diatomacez from the Geysers of Iceland ; 
and observes that the abundance of Diatoms in the thermal waters 
of Central and Southern Europe warrants us in expecting large 
additions to the Icelandic Flora from this source alone. Dr. Cohn 
has described Oscillatorize from hot springs containing sulphates, 
and ascribes the elimination of sulphuretted hydrogen to the action 
of these organisms. Mr. Edwards, in the paper above referred to, 
suggests the importance of an examination of the hot sulphureous 
springs of California for these organisms and for Diatomacez. It 
would, he remarks, be exceedingly interesting to ascertain by com- 
parison of specimens from sulphureous and neighbouring fresh- 
water springs, what modifying effect the thermal conditions have 
had on the form of the various species. This is a most important 
method of inquiry, and one which must be fully followed up; for, 
by its means, we may hope ultimately to arrive at a definite know- 
ledge of the exact relations of living forms to the conditions of their 
existence. 
