Dec, 8, 1881 | 
NATURE 
pas 
earthquake of January, 1869, the direction of the loud banging 
sounds like artillery was carefully marked against a peak in the 
Naga Hill range. Bearings by the prismatic compass subse- 
quently sent to Calcutta to Dr. H. B. Medlicott, turned out to 
be within 3° of the true line to Cheduba and Ramree, the active 
volcanic centre, 550 miles off. I cannot exactly see how the 
difference of the z7¢enstty assists us in directing to the sound. I 
find I judge that best by facing it and remaining still, and verify 
the direction best by /ooking (with the eyes only) about 10° to 
right, and then 10° to left, which, if I do not move the head, 
soon enables me to fix by eye the direction pretty close. 
Sibsagar, Asam, October 27 S. E. PEAL 
An Audible Photometer 
IN your issue of September 22 (vol. xxiv. p. 491, British Asso- 
ciation Reports) Mr. Lant Carpenter mentions an idea of his about 
an ‘‘audible photometer.” The same idea occurred to me some 
six months ago. As my plan seems to be much more simple than 
Mr. Carpenter’s, dispensing with intermitting beams and rotating 
disks, perhaps you will allow me a little space to describe it. I 
require only one photophonic receiver, whereas Mr, Carpenter 
mentions “‘ two precisely similar receivers,” which is difficult, if 
not wholly impossible, to obtain. A is a small battery, B an in- 
duction-coil with the ordinary vibrating magnetic interrupter, 
and with a high-resistance secondary coil; c is the Wheatstone- 
bridge combination, s E a selenium cell, with its working surface 
turned to the scale £; Risa high resistance of about the value 
of the selenium cell ; @ is a sliding contact, T a high-resistance 
telephone. Now I place on the scale © a standard candle at a 
distance ¢@ fromselenium cell, and move the sliding contact till no 
sound is emitted from the telephone. Then the wire connections 
are left wholly unaltered, and the candle is taken away. Now I 
place the light I wish to compare with the standard candle on 
the scale £, and move it along the scale till the telephone is again 
silent. Be the distance of the light from the selenium cell now 
D, then its luminous intensity is 
Dp 
a? 
As, on after-thought, I greatly doubted the fitness of selenium for 
photometric purposes (which d ubts became the stronger the 
more I read about the subject), I did not pursue my idea, which 
could only result in an addition to the long list of practically 
useless photometers. The above may perhaps be used as a col- 
lege experiment for demonstrating the Jaw of the square of 
distances. J. W. GILTAy 
Delft, November 21 
standard candles. 
Extraordinary Atmospheric Phenomenon 
TINCLOsE a paragraph from the Glasgow Avening Citizen of this 
date relating to that peculiar form of lightning known as fire-balls. 
The explanation of the explosion in the funnel is, I think, 
erroneous, it having been caused by the explosion of the fire-ba!l, 
thus driving out the smoke by the fire-doors. The aurora was 
very bright here on Wednesday evening, showing Piazzi Smyth’s 
line with a small direct vision spectroscope. Before the eye 
became sufficiently sensitive for measurement, clouds cut off the 
bright part. The aurora was a general bright northern glow 
without streamers, and was observed brightest a litile after eight 
(p.m.). These notes may be of use to you in connection with 
those of other observers. J. B. HAnNay 
Cove Castle, Loch Long, N.B., November 25 
Extraordinary Phenomenon of the Storm 
Those on board the Campbelton Steamer A‘n/och (Capt- 
Kerr), which left Greenock on its usual run about half-past 
eleven o’clock on Tuesday morning after the storm that raged 
during the night, had a somewhat extraordinary experience 
while passing down the Firth. The vessel was enveloped in a 
dense shower of hail, and for some time it was awfully dark, and 
occasionally the vessel was lit up by vivid flashes of lightning. 
One of the flashes was very bright, and its shape was something like 
that of the arteries of the human body, with a central column all 
shattered and broken, About noon, while opposite the Cloch Light- 
house, and not far from the shore, the captain observed immediately 
over the ship what appeared to be a series of clear balls of 
lightning, each about a foot in length, and resembling a chain, 
except that they were disconnected. This phenomenon was 
quickly succeeded by an explosion in the funnel of the steamer, 
and several balls of fire upon the bridge running about, and then 
bounding off into the water. The first impression of the spec- 
tators was that something had exploded on board, but on inquiry 
it was found that this was not the case. The mate stated, how- 
ever, that a ball of lightning had almost struck him where he 
stood. A fireman rushed upon deck to see what had happened, 
as the engine-room was filled with smoke, and a choking sensa- 
tion was experienced below. ‘The explanation appears to be 
that a portion of the lig’ tning had passed down the funnel until. 
its force was spent by the fire, and the sudden recovery cf the 
drauvht of the funnel afterwards accounted for the loud report 
that was heard. The captain, in his long experience at sea, 
never encountered such a pheno enon before, and it may be 
taken as an indication of the extraordinary atmospheric forces 
which had been at work during the storm, and which seemed to 
centre in this locality. 
Papin 
In the review of my ‘Life and Letters of Papin’! in 
NATURE, vol. xxiv. p. 378, the hope is expressed that I might 
succeed ‘‘to fill the /acun@ in the career of this remarkacle 
man.” The only important blank remaining now in our know- 
ledge of Papin’s life consists in our ignorance of the time of his 
death. We may rest assured that he died in London, and there- 
fore this blank is not likely to be filled but by a person who is 
familiar with the city and its inhabitants of the present and of 
the beginning of last century. Papin died about 1712. During 
1709 he lived at ‘Madam Portal chez M. Charron, apothécaire 
cans Compton Street, proche St. Anne.” As it is not probable 
that he chanved his lodgings before his death a search in the 
registers of the district to which Compton Street belonged (if 
they are in existence) would lead to results equally important for 
the history of science and for that of technology. Maybe a 
reader of this note who enjoys such opportunities will render me 
his assistance in this thankful task. 
I avail myself of this opportunity of correcting a few slight 
mistakes which have found their way into the otherwise excellent 
résumé, Not Papin but Leibnitz is the author of the letter of 
February 4, 1707. which contained the first idea of the ‘* hot-air 
engine.” Leibnitz is therefore the inventor of the samé. “Pnct 
boat, in which Papin left Cas-el in 1707 to sail to Bremen, was 
not a ‘“‘steam propeller boat,” but a small ship with paddle- 
wheels to be worked by the sailors. It was not Papin’s inten- 
tion to proceed to England in that boat. He left Cassel with 
proofs of the favour and goodwill of the Landyraf, which re- 
mained unchanged to the end. Lastly, before Papin no steam- 
engine existed; he is the real inventor of the same, for he in 
1690 first announced the idea, and tested it by experiments of 
utilising the pressure of steam as motive power for engines. 
This, his first engine, had a piston inside a cylinder. Such an 
arrangement was not at all new at that time; other machines 
had the same, as, for instance, the gunpowder engine of 
Huyghens, which suggested the invention of Papin. Leibnitz 
corresponded with the inventor about this engine much later, 
and made valuable propositions, but the correspondence of these 
t Leibnizen’s und Huygens’ Briefwechsel mit Papin, nebst der Biographie 
Papin’s und einigen zugehérigen Br efen und Artenstiicken. _ Bearbeitet und 
auf Kosten der Kéniglichen Preussischen Akademie der Wissenschaften 
herausgegeben von Dr. Emst Gerland. Berlin, 1881. Verlag der Kénig- 
lichen Akademie der Wissenschaften. 
