Fan. 26, 1871] 
resistance above 30,000 would not be a singular case. I 
could tell something of galvanometers of 1869, comparable 
only to submarine cables of 1857. I refrain :—but let 
makers of galvanometers, Ruhmkorff coils, and electro- 
magnets beware; surely NATURE will find them out if 
they do not reform before 1872. W. THOMSON 

THE GAUSSIAN CONSTANTS OF TERRES- 
TRIAL MAGNETISM 
THINK you will be doing good service to the cause 
of Natural Science by giving insertion in your valu- 
able pages to the following translation of a notice which 
appeared in No, 1,825 of the Astronomische Nachrichten 
(Vol. 77, p. xi.), on the subject of Prof. Petersen’s re- 
computation of the Gaussian Constants of Terrestrial 
Magnetism, in aid of which the British Association at 
their last meeting voted a-grant of money. It has been 
communicated to me by Prof. Erman of Berlin, who, in 
reference to the grant in question, writes as follows :— 
“This new act of British generosity would in other times 
have scarcely needed a special mention, being equalled 
by so many former ones of the same kind ; but in the 
present moment, when the raging war makes petty 
jealousies spring up between our two befriended [friendly] 
nations, it is a most sacred duty to publish the fact of 
two Prussians having found in England a most generous 
and most wanted help for their scientific endeavours.” 
Mr. Petersen’s calculations are progressing in a very 
desirable manner, and he hopes fully to bring them to 
their end (D.v.). J. F. W. HERSCHEL 
Collingwood, Jan. 21 
TRANSLATION 
“We learn by a communication from Prof. Erman that 
M. Petersen, of Kiel, has undertaken to extend his great 
work on Terrestrial Magnetism, so as to afford for the 
whole earth, and for the epoch 1829, a Fundamental 
Determination of the Potential Constants, which, accord- 
ing to laws yet unknown, are subject to secular variation. 
From the knowledge of these fundamental values so 
obtained by the researches of Erman and Petersen, will 
then come to be securely connected, as a second step in 
advance, the determination of the laws of secular change. 
Since, however, the material obstacles to so laborious a 
work, with whatever personal devotion, would have proved 
insurmountable without public aid, it becomes our duty 
most gratefully to announce that such aid has been 
granted from the same quarter which afforded it to the 
earliest portion of this undertaking. The British Associa- 
tion for the Advancement of Science, at its last annual 
meeting, has appointed a committee, consisting of Sir J. 
Herschel and Prof. A. Erman, for the purpose of engaging 
M.H. T.R. Petersen to prosecute the continuation of 
his computations of the constants in question for 1829, 
so as to embrace all observations not included in the 
previous calculations, and to this end has placed a sum 
of 50/. at their disposal. 
“Tn pursuance of this object Prof. Erman addresses to 
NATURE 
the readers of this notice his request for the communica- | 
tion of citations of, or references to, works and treatises 
or essays in which may be found recorded measured 
values for any station of the globe, of the magnetic | 
declination, inclination, and intensity during any portion 
of the last ten years, as also any researches on the annual 
variations of these elements at determinate stations. 
course it is not meant to call for even an approximately 
complete catalogue of works of this kind, to furnish which 
would of itself require no small amount of labour. But 
many astronomers [and others] must have access to a 
variety of journals, accounts of travels, records of 
measures and observations, &c., which may not have 
come under the notice of Messrs. Erman and Petersen, 
* Prof. Dr, C. A, F. Peters, Direktor der Sternw&rte in Altona, 
Of | 

249 

notices of which, communicated to” the Editor of the 
A stronomische Nachrichten * in the form of a letter, with 
a postcriptum or memorandum such as :—Magnetic Ob- 
servations for 18. . areto be found in . . Volume 
page are requested.” 

ACCOUNT OF THE AUGUSTA ECLIPSE 
EXPEDITION 
je consequence of the unfortunate wreck of the Psyche 
on a sunken rock on the coast of Sicily, about nine 
miles north of Catania, the arrangements of the Sicilian 
Expedition were considerably modified. Catania was 
made the headquarters of the expedition, and the garden 
of the Benedictine Monastery was given up by the 
authorities of the city to the English and American 
observers. It was finally arranged that Prof. Roscoe 
should take charge of the Etna Expedition, and I was 
asked by Mr. Lockyer to take charge of the Expedition to 
Augusta. Mr. Brett, Mr. Burton, Mr. Clifford, Mr. Ran- 
yard, Mr. Samuelson, and myself formed the party. 
It was also arranged with Mr. Ranyard at Catania, 
that on the morning of the 22nd, he and another of 
our party should drive some miles up from Augusta in 
the direction of the hills of Carlentini, to observe the 
Eclipse. At Augusta we were to live in camp, and Colonel 
Porter, with a body of sappers, had been landed there by 
the Pysche on her way to Naples. 
Mr. Brett and Mr. Ranyard went first to Augusta to 
make arrangements with Colonel Porter for our encamp- 
ment and observatory, and they met with every assistance 
from the Syndic of the City of Augusta, and were very 
kindly received by the Italian astronomers, among whom 
were Prof. Cacciatore, Prof. Donati, Father Secchi, and 
Father Denza, who were stationed inside the fort. Our 
encampment, and a wooden observatory sixty feet long, 
were pitched on the southern slopes of the glacis of the 
fort, with a full view of the sea to the east. 
I cannot speak too highly of the way in which Colonel 
Porter exerted himself to make all arrangements satis- 
factory and complete, and even to introduce elements of 
comfort into our camp life; and the energetic way in which 
his men carried out his instructions is beyond all praise. 
Up to Monday the rgth, the terraces of the Monastery at 
Catania were made the general practising ground, and 
those who were to observe for polarisation, except Mr. 
Ranyard, who was at Augusta, tested and compared their 
instruments for rapidity of correct observation, and for 
delicacy. 
For my own telescope I had two eye-pieces, one with 
plates of double-rotating quartz, and the other with a 
Savart polarimeter. When the polarisation was not very 
strong, I found the polarimeter more delicate than the bi- 
quartz for detecting the plane of polarisation, and with it 
I was able to measure the amount of polarisation readily. 
On observing the same points with Mr. Griffiths, who 
also used a Savart polarimeter, we found that in from ten 
to fifteen seconds we could determine the plane and 
amount of polarisation, and in some cases we found that 
our readings for both were absolutely identical. 
At about 6.30 on Monday evening, and again soon after 
7 o'clock, when Mr. Clifford and I were on the sea on our 
way to Augusta, we saw a brilliant display of the zodiacal 
light, consisting of brilliant pink streamers, stretching up 
perpendicularly to the horizon, the planet Jupiter being just 
on the most brilliant streamers. Towards the north and 
round the horizon there were also streamers and a faint 
hazy light, and the sky became covered with a pinkish 
mauve colour. One of these displays was also seen by 
the rest of our party at Augusta. 
As the evening grew darker, there was strong phos- 
phorescence on the sea. The drops scattered by the oar 
as it struck the water glowed with phosphorescent light, 
and the forms of the eddies, caused by the bending of the 
oar, were distinct and brilliantly illuminated, 
