114 
NATURE 
[Mov. 30, 1882 
Warsow railway line between Pljusse and Pleskau, also along 
the Moscow Railway line the forest was on fire. Thousands of 
people had been ordered out to try and extinguish the Hames, 
but all attempts in this direction proved futile, the only thing 
that could be done was to confine the limits of the fires. 
Dr. KING, the Superintendent of the Royal Botanic Gardens, 
Calcutta, has recently issued his report for the year 1881-82. 
The Calcutta Garden may be said to be the centre of botanical 
work in India, and none can probably claim a greater antiquiiy, 
as the report before us is stated to be the nine‘y-fifth annual 
report of these Gardens, Like its predecessors the report opens 
with a description of the changes and improvements in the 
Garden itself, points which are, of course, only of local interest. 
On the subject of india-rubber yielding plants—a subject of very 
great importance—Dr. King says: ‘‘Clara rubber (Manihot 
Glazioviz) continues to grow well here ; our trees are beginning 
to seed, and from their produce I was able to distribute during 
the year a good many seedlings to tea-planters in Assam, Chitta- 
gong, and elsewhere. A species of Landolphia, which is one of 
the sources of the rubber collected in Eastern Africa, has (thanks 
to the exertions of Sir John Kirk, Her Majesty’s Consul-General 
at Zanzibar) been introduced to the Garden. From the seeds 
sent by Sir John Kirk a number of young plants have been 
raised, and these at present look very healthy. The cultivation of 
the plant yielding Para rubber (Hevea braszliensis) has been aban- 
doned, as the Bengal climate proves quite unsuitable for it. Of 
Castilloa, another South American rubber-yielder, we have as 
yet only eight plants, but it is being propagated as fast as 
possible,” Another important subject is that of the production 
of material; for paper-making, and of these plantain fibre 
seems to have occupied some attention. It seems that during 
the dry months, simple exposure of the sliced stems to the sun 
is a sufficient preparation for the paper-maker, provided the 
paper-mill be on the spot. What is still wanted is some cheap 
mode of removing the useless cellular tissue, so that the fibre 
may be shipped to England without the risk of fermentation 
during the voyage. The cultivation of the plantain for its fruit 
is so universal over the warmer and damper parts of India, and 
its growth is so rapid, that the conversion into a marketable 
commodity of the stems at present thrown away as useless would 
be an appreciable addition to the wealth of the country. The 
paper mulberry of China and Japan (Lroussonetia papyrifera) is 
being tried in the Garden, as well as in the Cinchona plantations 
in Sikkim, as it is well known that the bark yields a splendid 
paper material, A plant which appears to be at present un- 
known, but which Dr. King thinks will prove a species of 
Eriophorum, is also favourably reported upon. Under the head 
of ‘*Other Economic Plants,” mahogany, the rain-tree, and the 
Divi Divi, are said to be in considerable demand. A large in- 
terchange of seeds and plants has been effected during the year, 
with other parts of India, as well as with England and the 
Colonies. 
No further news of the wreck alleged to have been seen near 
the Island of Waigatz has come to hand. Capt. Burmeister, of 
the Louise, who parted from the Dijmphna and the Varna in 
September last, is of opinion that the vessel seen is the Varna 
in her winter-quarters, simply with masts and yards lowered, 
which seem to be corroborated by the recent discovery, that the 
original message says west of Waigatz Island, where the wreck 
could not have drifted. 
PAkTS 11 to 16 of Dr. Chavanne’s edition of Balbi’s Geo- 
graphy (Vienna, Hartleben) have appeared ; they are largely 
devoted to the Austro-Hungarian monarchy. 
WE need scarcely mention that Oxford is the seat of the New 
Science Club, to the meeting at Trinity College in connection 
with which we referred last week. 
IN the last sitting of the Syndicat d’Electricité M. Jablochkoff 
described a new element which he has invented, and which 
consists of sodium for the electro-positive plate, the ne- 
gative being, as usual, carbon, M. Jablochkoff does not 
use any exciting liquid but merely sends into his elements 
by the instrumentality of an aspirator, a current of air 
saturated with moisture. He says that soda is dissolved and 
falls to the bottom of the box where his elements are kept so 
that it may be easily collected and sold at a high price, being 
pure except for a smali quantity of carbonate and of nitrate. 
According to his statement the electromotive force of this element 
is about 4 volts. 
THE additions to the Zoological Society’s Gardens during the 
past week include a Green Monkey (Cercopithecus call:trichus @ ) 
from West Africa, presented by Mrs. Gretton ; a Northern Lynx 
(Felis lynx) from the Carpathian Mountains, presented by the 
Count Constantin Branicki ; an I:abelline Lynx (Fé/is isabellina) 
from Tibet, presented by Capt. Baldock; a Forster’s Milvago 
(Afilvago australis) from Falkland Islands, presented by Dr. A. 
M. McAldonie ; an Annulated Snake (Leplodira annulata) from 
Honduras, presented by Mr. R. E. Seabrooke; a Short-tailed 
Wallaby (Halmaturus brachyurus 2) from West Australia, three 
Blue-crowned Hanging Parrakeets (Loriculus galgulus) from 
Ceylon, deposited; a Moloch Monkey (Cad/ithrix moloch) from 
Brazil, two Snowy Owls (Wyctea nivea 8 ? ), European, a Shore 
Lark (Zremophila alpestris), British, purcbased ; a Great Bustard 
(Otis tarda), European, received in exchange. 
ON THE TRANSITS OF VENUS. 
“TRANSITS of Venus usually occur in pairs ; the two transits 
of a pair being separated by only eight years, but between 
the nearest transits of consecutive pairs more than a century 
elapses. We are now on the eve of the second transit of a pair, 
after which there will be no other till the twenty-first century ot 
our era has dawned upon the earth, and the June flowers are 
blooming in 2004, When the last transit season occurred the 
intellectual world was awakening from the slumber of ages, anda 
that wonderous scientific activity which led to our present 
advanced knowledge was just beginning. What will be the state 
of science when the next transit season arrives God only knows, 
Not even our children’s children will live to take part in the 
astronomy of that day. As for ourselves, we have to do with 
the present, and it seems a fitting occasion for noticing briefly 
the scientific history of past transits, and the plans for observing 
the one soon to happen. 
When the Ptolemaic theory of -the solar system was in vogue, 
astronomers correctly believed Venus and Mercury to be 
situated between the Earth and the Sun, but as these planets 
were supposed to shine by their own light, there was no reason 
to anticipate that they would be visible during a transit, if indeed 
a transit should occur. Yet, singularly enough, so far back as 
April, 807, Mercury is recorded to have been seen as a dark spot 
upon the face of the Sun. We now know that it is much too 
small to be visible to the naked eye in that position, and the 
object observed could have been nothing else than a large sun- 
spot. Upon the establishment of the Copernican theory it was 
immediately perceived that transits of the inferior planets across 
the face of the Sun must occur, and the recognition of the value 
of transits of Venus for determining the solar parallax was not 
long in following. The idea of utilizing such transits for this 
purpose seems to have been vaguely conceived by James Gregory, 
or perhaps even by Horrocks; but Halley was first to work it 
out completely, and to him is usually assigned the honour of the 
invention. His paper, published in 1716, was mainly instru- 
mental in inducing the governments of Europe to undertake the 
observations of the transits of Venus of 1761 and 1769, from 
which our first accurate knowledge of the Sun’s distance was 
obtained. 
When Kepler had finished his Rudolphine tables they 
furnished the means of predicting the places of the planets with 
some approach to accuracy; and in 1627 he announced that 
* An address delivered before Section A of the Am‘rican Association for 
the Advancement of Science, on August 23, 1882, by Prof. Wm. Harkness, 
Chairman of the Sectiou, and Vice President of the Asscciation. 
