184 NATURE 
[JUNE 22, 1899 
which are the malaria-bearing species of mosquito in the 
locality chosen, and then inquire whether it is possible, by 
filling up the particular puddles in which they breed, to 
exterminate malaria in a given district. 
On Saturday last, the French naval authorities, acting in con- 
junction with Mr. Marconi, conducted some successful experi- 
ments with wireless telegraphy, between a ship and the shore 
in the English Channel. The French storeship Vienne was 
used for the purpose. Up to Saturday the distance between 
the South Foreland and Boulogne, about twenty-eight miles, 
was the greatest space through which these messages have been 
transmitted. On Saturday messages were sent between the 
vessel and the English coast from off Boulogne, and afterwards 
at intervals, until the vessel was twelve or fourteen miles away 
from that port. The greatest distance through which the 
messages were transmitted was forty-two miles. It is stated 
that Mr. Marconi’s method of limiting the area of influence of 
the waves used was successfully applied. The messages were 
sent at will either to Wimereux or to the South Foreland, 
without the other station being able to intercept them. 
A MARINE exploring expedition to the mid-Pacific, under 
the direction of Prof. A. Agassiz, is being arranged by the U.S. 
Commission of Fish and Fisheries. The expedition will leave 
San Francisco about the middle of August, and proceed directly 
to Tahiti, in the Society Islands, which will be made the head- 
quarters while the Paumotu Islands are being explored. In 
this archipelago, which is about 600 miles long, the d/batross 
will pass six or eight weeks. After returning to the Society 
Islands, the vessel will go to the Tonga, or Friendly Islands, 
where a week or ten days will be spent. Thence the vessel will 
sail for the FijieIslands, where a short stay will be made, and 
thence to the Marshall Islands, visiting a number of the Ellice 
Islands and Gilbert Islands on the way. Six or seven weeks 
will be devoted to the exploration of the Marshall Islands. 
Between the Marshall Islands and the Hawaiian Islands, and 
between the latter and San Francisco, a distance of over 4000 
miles, a line of deep-sea dredgings will be run, deep-sea tow- 
nets being used while the dredging is going on. The A/ébatross 
is expected to return to the United States in April next year. 
Every effort is being made to thoroughly equip the vessel for 
deep-sea dredging, trawling and sounding ; surface and inter- 
mediate towing ; shore seining ; fishing trials with lines and 
nets; land collecting, and other branches of the work. The 
newest apparatus for deep-sea and plankton: investigations will 
be supplied. Special appliances are being constructed for use 
in the very deep water to be found about some of the islands. 
A PARAGRAPH on the thermal conductivity of cast iron, as 
determined by Messrs. E. H. Hall and C. H. Ayres, appeared 
in NaTurRE of April 13 (p. 563). The thermal conductivity of 
the cast iron used was found to be about 0°1490 at 30°C. Mr. 
I. Thornton Osmond, Dean of the Pennsylvania State College, 
calls our attention to the fact that this result differs from values 
obtained under his direction in 1894, and described in the 
Physical Review of that year (vol. ii. No. 3, Nov.—Dec.). 
For the cast iron used in this investigation, the thermal 
conductivity from 60° C, to 90°C. or 100°C. was found to bea 
little over 0°09 ; and from 150° C. to 200° C. a little over o°11. 
Mr. Osmond adds: ‘‘ Though believing, from theoretical con- 
siderations, the conductivity to be a direct function of temper- 
ature, these figures were somewhat surprising; and I made 
preparation to have the work repeated through a greater tem- 
perature range and with great care; but this was never carried 
into effect. ‘The method used was that of Principal Forbes, 
substituting thermopile and galvanometer for mercury ther- 
momieters, thus greatly reducing the cavities in the bar.” 
NO. 1547, VOL. 60] 
WE regret to learn that among other steps taken in reducing 
the expenditure of the Colony of Jamaica, it has been decided 
to withdraw the annual contribution towards the Weather 
Service, which has for the last eighteen years been under 
the control of Mr. Maxwell Hall, and to substitute a vote of 
50/. for the collection and tabulation of statistics of rainfall and 
temperature. The letter from the Colonial Secretary seems 
to suggest that one reason for the step taken was that the 
full co-operation on the part of other Colonies and countries, 
which was necessary to make the scheme a complete one, was not 
forthcoming. The Service consisted of one first-class station, six 
stations of the second and third classes, and about two hundred 
rainfall stations. The vote was a very small one, and the 
director appears to have done good work, and to have been suc- 
cessful in issuing storm warnings and rainfall forecasts, although 
the latter could not reach those principally interested. Various 
useful investigations have been undertaken and published in the 
Jamaica Weather Reports, or elsewhere. 
THE volume of hourly means of the readings obtained from 
the self-recording instruments at the five observatories under the 
Meteorological Council, just published for the year 1895, com- 
pletes the lustrum 1891-1895 ; an appendix has therefore beem 
added to the usual tables for the year in question, showing the 
mean values for that period. In addition to these values, hourly 
and other means of pressure, temperature and rainfall are given 
for four observatories, for a period of twenty-five years, and of 
sunshine for fifteen years. These averages afford valuable 
data for climatological or other more minute investigations. 
Further, in deference to a recommendation of the international 
meteorological conference at Paris in 1896, the hourly readings 
for some elements are given for two stations—Valencia Observ- 
atory as a typical Atlantic Coast station, and Kew Observatory 
asa typical inland station, and it is intended to continue this 
departure in future volumes, 
PRor, ARRHENIUS contributes to the Revue Générale des 
Sciences an interesting account of his investigations into the 
causes of secular variations of temperature at the earth’s 
surface. It is shown that widespread changes of mean temper- 
ature are more likely to be due to variations in the proportion 
of terrestrial rays absorbed by the atmosphere than to any 
variation connected with the solar rays, and that the absorption 
of terrestrial rays is most likely to be affected by changes in the 
amount of carbonic acid present in the atmosphere. Using 
Langley’s data, it is calculated that if the amount of carbonic 
acid were diminished by a little more than half, the temperature 
would be lowered by about 4°°5 C., while an increase to two and 
a half or three times the present amount would raise the temper- 
ature about 8°°5 C., corresponding to the conditions of Glacial 
and Eocene times respectively. This calculation gives rise to 
some interesting speculation as to the possibility of such 
changes having taken place as the result of volcanic or erosive 
action, and the effect of the artificial consumption of carbon in 
raising the temperature of the air. 
THE National Geographic Magazine for May contains a paper 
by Mr. J. B. Leiberg, entitled ‘‘Is climatic aridity impending 
on the Pacific slope?’’ The arid non-forested regions of 
eastern Oregon, and the semi-arid, sub-humid, and humid forest 
tracts are examined separately, and in each case evidence is 
found of adverse climatic change taking place in the direction of 
aridity. 
THE parietal eye, with its adjacent organs, of the New Zea- 
land Tuatera (Sphenodon) receives attention at the hands of Dr. 
A. Dendy in the May issue of the Quart. Journ. Micr. Soc. 
This functionless eye, which, although deeply buried in the 
integument, is better developed in the reptile named than in 
