SCIENTIFIC SUMMARY. 
113 
and south poles, produced by tlie south and north poles of the block. 
Expt. 2. Place the wire reversed on the block, i.e. lay the north pole of the 
wire on the north pole of the block, and hammer as before. Tested again 
by the needle, the wire exhibits its poles reversed. Expt. 3. Lay the wire 
as in Expt. 1., and hammer ; the original polarity is restored. Finally, by 
changing the position of the wire, the pole maybe changed and rechanged 
as long as the wire lasts. This experiment would seem to represent well 
the magnetising action of the earth. The block personates the earth with 
its magnetism, which is not less comparatively than that of the cast iron. 
Were the wire to remain for a considerable time lying on the block, it would 
be magnetised. The hammering effects this quickly. 
Obtaining High Temperatures in Liquids. — A very useful invention of 
Mr. Coffey is now to be seen in operation at Messrs. Doulton and Watts’s, of 
Lambeth. It is a new mode of obtaining high temperatures for the evapo- 
ration of liquids without the use of high pressure or superheated steam, and 
is, in fact, a modification of the circulating system, heated water being re- 
placed by heavy paraffine oils. These circulate exactly like water. A close 
system being made, the oil heated in a coil of pipe placed in a furnace rises 
first to an air-tight tank, from which it runs through pipes and the jackets 
of pans, descending as it cools to the coil of pipe in the furnace. With this 
apparatus a temperature of G00° or 700° F. may be safely maintained with- 
out any of the risks arising from the use of steam at high pressures, and, as 
will be easily seen, with a much less expenditure of fuel. 
A Severe Test for a Lightning-Rod. — According to a recent number of 
the “Boston Journal of Chemistry,” a powder magazine at Venice, contain- 
ing 300,000 kilogrammes of gunpowder (about 300 tons) was struck by 
lightning this summer. The platinum point of the lightning-rod was melted, 
and the rod split and twisted, but the electric charge was safely conducted 
to the earth without doing any other damage. That lightning-rod may be 
said to have saved a city, for the explosion of such a quantity of powder 
would have laid all Venice in ruins. 
ZOOLOGY AND COMPARATIVE ANATOMY. 
Objections to Darwin's Theory of Fertilisation through Insect Agency. — At 
the American Association for the Advancement of Science Mr. Thomas 
Meehan read a paper on this subject. He said that the discoveries of 
Darwin had disclosed wonderful apparent arrangements for fertilisation 
through insect agency ; but occasionally instances were found where, with 
the most perfect facilities, insects seemed to make no use of them. These 
had been considered as objections to a full acceptance of Mr. Darwin’s 
theories. The Salvia was an instance. The lower division of the anther 
acted as a petaloid lever, closing the throat of the corolla tube, which ought 
to throw the pollen on the back of the bee when it entered for the honey. The 
principle was perfect. But no insect is seen to enter. On the other hand, the 
humble bee, “without which,” Darwin says, “some species would die out 
in England,” bores a hole on the outside, through which it gets the honey. 
The humble bee thus seems to avoid its duties here. A similar state 
YOL. X. — NO. XXXVIII. I 
