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of the first of these two alloys for pure bismuth, the difference between 
Elliott’s pile and the pairs II. & III. will be rather greater. The pile by 
Messrs. Elliott, if made of the same metals as he employed, would have 
been reduced in power from 1 to 0 9. The construction of thermo-couples, 
on the plan he lias described, is comparatively easy. In about two hours 
he was able to make one, and in more experienced hands their construction 
would be still easier. An experiment was made with one of the piles to 
ascertain whether, when the heat was not directed centrally on the pile, 
much diminution of power would take place. There was less deviation, in 
consequence of the increase of the mean distance which the heat had to 
travel before it reached the soldering; but he believes that this defect 
might be remedied, probably without diminution of the power of the pile, 
by increasing the thickness of the face, and leaving the dimensions of the 
bars the same. 
Improved Bichromate Battery . — In a letter written to the Journal of the 
Franklin Institute, Mr. W. Poole Levison, of Cambridge, Massachusetts, says 
that in the spring of 1869, while making use of a small bichromate of 
potash battery, he discovered that the addition of nitric acid to the mixture 
of potassic bichromate and sulphuric acid, contained in its porous cups, 
conferred upon it the virtue of steadiness, without involving the evolution of 
annoying fumes. For over two months, during last summer, he had in 
almost constant action a combination of twenty-three large Bunsen cells 
charged with dilute sulphuric acid and the triple mixture mentioned, and 
1 ‘ set up ” openly upon the floor of his room. Not only did he work about 
it with perfect comfort, but left choice brass instruments in its immediate 
neighbourhood with impunity. Its energy never fluctuated, but after re- 
maining for some time steady, declined, precisely as if the electro-negative 
plates were bathed in nitric acid only. To a cooled mixture of potassic 
bichromate solution and sulphuric acid (perhaps preferably in atomic propor- 
tions) add nitric acid. The proportion of nitric acid may be greatly varied, 
as its office is merely to transfer oxygen. 
Opening of the Kepler Monument. — The following very interesting account 
of this is taken from Les Mondes (July 14). On the 24th of last June, the 
very small Swabian town named Weildiestadt, with hardly 2,000 inhabi- 
tants, was the scene of a festive gathering for the purpose of unveiling the 
statue of the celebrated Kepler, who was born in an humble cottage yet 
existing, and now known as Kylerhaus. The statue of the celebrated 
astronomer, executed in bronze, represents him seated on an arm-chair ; in his 
left hand, supported by a celestial globe, he holds a scroll, upon which an 
ellipse is delineated ; in his right hand he holds a pair of opened compasses. 
At the four corners of the pedestal, upon which the statue is placed, are 
smaller statues, representing Michel Mastin, the Tubingen professor who 
taught Kepler mathematics, and Nicholas Copernicus, Tycho Brahe, and 
Jobst Byrg, who assisted Kepler in making astronomical instruments. On 
the centre of the pedestal is simply placed “ Kepler; ” the other sides of this 
portion of the monument are embellished with bas-relief representations of 
incidents of Kepler's life. 
The Effect of Artificial Light on the Eyes . — The Chemical News takes the 
following interesting paper from Les Mondes. It is by M. V. Meunier. The 
