390 
NATURE 
[ fed. 10, 1870 
the maximum economical effect from gas, this result is best at- 
tained with burners of ample flow. Prof. W. D. Alexander de- 
scribes, in a letter to the editor, the results of a careful survey of 
the crater of Haleakala in the island of Maui. F. W. Clarke 
gives a new method of separating tin from arsenic, antimony 
and molybdenum, based on the solubility of the sulphides of 
tin in oxalic acid solution. EE. Billings, paleontologist of 
the Canadian Geological Survey, continues his notes on the 
Crinoidea, Cystidea and Blastoidea. A paper on anewspectroscope, 
with contributions to the spectral analysis of the stars, by 
Dr. Zollner, is translated from the Prcceedings of the Royal 
Society of Saxony. H. J. Clark has a paper on Polarity and 
Polycephalism, extracted from a forthcoming memoir on the 
anatomy and physiology of Licernari@, in which ke treats of 
the discussion that has of late years prevailed as to whether the 
lower compound denizens of water are individuals or organs 
forming only a part of anindividual, Dr. Sterry Hunt contributes 
a paper on Laurentian rocks in Eastern Massachusetts, in which 
he announces the discovery of Eozoén in the limestone of that 
district, by Mr. Bicknell. In a paper on the chemistry of 
common salt, Dr. Goessmann treats of the origin, occurrence and 
manufacture of salt. J. Lawrence Smith gives an account of the 
fall of meteoric stones in Alabama, with analyses, and points out 
the importance of a thorough re-examination of the mineral 
nature of meteoric stones. A. E. Verrillcontinueshiscontributions to 
zoology, from the Museum of Yale College, by describing Echino- 
derms and Corals from the Gulf of Californiaand gives also a note 
on the generic relations and synonymy of the Common Sea- 
Urchin of New England (Zuryechinus Drobachiensis) in which 
he replies to a criticism by M. Agassiz upon the author’s classi- 
fication of the species here referred to. E.S. Morse has ap 
on the early stages of Brachiapods, describing the developme 
of Terebratulina Septentrionalis, abundant in the waters of East- 
port (Maine) and Dr. Jeffries Wyman has a paper on the 
existence of a Crocodile in Florida, said to have been killed 
near the mouth of the Miami river and considered by the 
author, as belonging to the sharp-nosed species (C. acztzs). 
SOCIETIES AND ACADEMIES 
LonpDoN 
Royal Society, February 3.—The following papers were read: 
—‘‘ Note on an Extension of the Comparison of Magnetic Dis- 
turbances with Magnetic Effects inferred from observed Ter- 
restrial Galvanic Currents—and Discussion of the Magnetic 
Effects inferred from Galvanic Currents on days of tranquil 
magnetism.” By George Biddell Airy, Astronomer Royal. 
(Received December 22, 1869.) The author, referring to his 
paper in the Philosophical Transactions for 1868, stated that he 
had examined the whole of the galvanic currents recorded 
during the establishment of the Croydon and Dartford wires 
(from 1865 April 1, to 1867 October 24). The days of observa- 
tion were divided into three groups: No. I comprising days of 
considerable magnetic disturbance; No. 2, days of moderate 
disturbance, of which no further use was made and No. 3, 
days of tranquil magnetism. The points most worthy of notice 
are, that the general agreement of the strong irregularities, gal- 
vanic and magnetic, is very close ; that the galvanic irregulari- 
ties usually precede the magnetic, in time and that the northerly 
magnetic force appears to be increased. The author remarks 
that no records appeared open to doubt as regards instrumental 
error, except those of western declination ; and to remove this 
he had compared the Greenwich curves with the Kew curves 
and had found them absolutely identical. In the discussion of 
the galvanic current-curves, on days of tranquil magnetism, for 
independent examination of the galvanic laws, the author 
explained the method of measuring the ordinates and connecting 
the measures into expressions for magnetic action, at every hour, 
grouping the measures, at the same nominal hour, by months and 
taking their monthly means for each hour. As these exhibited 
sensible discordance, they were smoothed by taking the means 
of adjacent numbers, taking the means of the adjacent numbers 
of the new series and so on, repeating the operation six 
times. The author explained the theory of this process and 
the way in which it tends to degrade the periodical terms of 
higher orders, He then explained an easy method of resolving 
the numbers so smoothed, into periodical terms recurring once or 
twice, or thrice in the day, &c. and applies the method to the 
numbers for every month. When these quantities (which from 
month to month are perfectly independent) are brought together 
in tables, they present such an agreement, with gradual change 
accompanying the change of seasons, as to leave no doubt of their 
representing a real law of the diurnal changes of the galvanic 
currents. They also show the existence of a constant turn 
towards the nerth (explaining the apparent increase of force to 
the north observed in the results for days of great disturbance), 
and a still larger force towards the west (also well marked on the 
days of great disturbance). No light is obtained as to the origin 
of these turns; but they appear to be probably pure galvanic 
accidents, depending on the nature of the earth-connections. 
The author then exhibited, in curves, the diurnal inequalities of 
magnetism which the galvanic currents must produce. The 
form generally consists of two parallel lobes, making with the 
magnetic meridian an angle of nearly 60° from the north towards 
the west. The greatest east-and-west difference of ordinates, in 
the month of April, is o’00044 of total horizontal magnetic force; 
it corresponds in the hours to which those ordinates relate, 
nearly with the ordinary diurnal inequality. But it is much 
smaller than the ordinary diurnal inequality and the daily law 
of the galvano-magnetic inequality differs greatly from that of 
diurnal inequality. For the greater part, therefore, of diurnal 
inequality the cause is yet to be feund. 
“On the fossil mammals of Australia.—Part III. Diprotedon 
australis, Owen.” By Prof. Owen, F.R.S., &c. Received 
December 10, 1869. In this paper the author communicated his 
descriptions of Difvotodor australis, with figures of the fossil 
remains at his command, which have been received from various 
localities in Australia, since the first announcement of this genus 
founded on a fragment of lower jaw and tusk described and 
figured in the ‘f Appendix” to Sir Thos. Mitchell’s ‘‘ Three 
Expeditions into the Interior of Eastern Australia,” Svo, 1838. 
The fossils in question include the entire cranium and lower 
jaw, with most of the tecth, showing the dental formula 
of: i cieaeh ge sy m 29 =28 3 portions of jaws and teeth 
i ON res 
exemplifying characteristics of age and sex ; many bones of the 
trunk and extremities. The author described the skull and teeth 
and the result of the comparisons, establishing the marsupial charac- 
ters of Dzfvolodon and its combination of characters of AZacrofus 
and Phascolomys with special modifications of its own, which are 
more fully and strongly manifested in the bones of the trunk 
and limbs, subsequently described. The pelvis and femora pre- 
sent resemblances to those in Profescidea, not hitherto observed 
in any other remains of large extinct quadrupeds of Australia. 
But in all the bones described, essentially marsupial characteristics 
are more or less determinable. A summary of the characters of 
Diprotodon illustrated the conditions of its extinction, its analo- 
gies with the AZevatherium, its affinities to existing forms of 
Marsupialia and the more generalised condition which it mani- 
fests of that mammalian type. A table of the localities, in 
Australia, from which remains of Difrofodon have been obtained 
and a table of the principal admeasurements of the skeleton, are 
appended to the text. 
Royal Astronomical Society, January 16.—Third meeting 
of the Session.—Mr. De la Rue, vice-president, in the chair. 
The chairman announced that the president, though he was 
recoyering his health, was not able to take the chair. Thirty-one 
presents were announced and the thanks of the society voted to 
their respective donors. The first paper read was a communica- 
tion from Sir John Herschel, having reference to a supplementary 
list of eighty-four double stars observed at Slough since the year 
1820. Amongst these were many observed by the elder Struye 
and an interesting portion ef the communication referred to the 
relation between Sir John Herschel’s estimate of the magnitudes 
of stars and Struve’s. It appeared from the comparison that 
Herschel’s magnitude 30 corresponded to Struve’s 2°6 and the 
difference gradually widened from successive magnitudes until 
from the lowest orders the two lists were altogether dis- 
cordant. A similar relation was observed (we believe by 
Mr. Knott) between the magnitudes in Admiral Smyth’s 
Ledford catalogue and Argelander’s estimates. — A com- 
munication from Mr. Joynson, having reference to observations 
made on occultations and on phenomena of Jupiter’s satellites, 
was then read.—In a paper containing a list of occultations, 
Captain Noble referred to an estimate, by Mr. Penrose, of the 
latitude of the former’s observatory as deduced from an occulta- 
tion of ¢ Ceti.—The next paper, by Commander Davison, on the 
November meteors as scen at Santa Barbara, California, con- 
