of the leisure which he might have devoted to original research. As an honorary situation, without profit or emolument of any kind, but occasioning considerable expense to the individual, a stranger to the nature of its duties would suppose the office of President of the Royal Society, for a man of science, not only the most elevated but the most agreeable possible. It undoubtedly should be so; but it never can be so, as long as pretension to knowledge, vanity, and presumption, are more common (and they will always be more intrusive) than real knowledge, modesty, and diffidence. The pleasures of office, and especially of honorary office, are generally in anticipation and imaginary- the trials and troubles, real and incessant. These are the rocks and glaciers, the storms and torrents of the Alpine heights; the other, the rosy hues of reflected light, lost on near approach, -to be seen only in the distance, at which all asperities are invisible.

CHAPTER IV.

LETTERS TO HIS BROTHER. -RESEARCHES ON ELECTRO-MAGNETISM.
LETTER TO HIS MOTHER.EXTRACT FROM NOTE-BOOK EXPRESSIVE OF
STATE OF MIND. FURTHER RESEARCHES ON ELECTRO-MAGNETISM.-
EXCURSION TO IRELAND.— EXPERIMENTS ON THE ELECTRICAL PHE-
NOMENA EXHIBITED IN VACUO. HIS LAST VISIT TO HIS NATIVE
PLACE. LETTER TO HIS FRIEND MR. POOLE. RESEARCHES ON THE
FLUIDS IN THE CAVITIES OF CRYSTALLINE MINERALS. LETTER TO
HIS BROTHER FROM SCOTLAND. - VERSES ENTITLED "THE EAGLES.".
A NEW PHENOMENON OF ELECTRO-MAGNETISM. HIS SUGGESTION TO
MR. FARADAY, WHICH LED TO THE DISCOVERY OF THE LIQUEFACTION
OF MANY OF THE GASES. - PROPOSAL FOR THEIR APPLICATION AS
MECHANICAL POWERS. HIS RIGHTS ON THE SUBJECT VINDICATED. →→→→→→
LETTER TO MR. EDMUND DAVY FROM SCOTLAND. LETTER TO HIS
BROTHER. VERSES ON LORD BYRON WHILST LIVING. VERSES ON

HIM AFTER HIS DEATH.-VERSES WRITTEN AT ASHBURNHAM.

To return to the narrative previous to his election as President to the Royal Society. After spending about a fortnight with my brother in London, I left him to go into Cornwall on a visit to my mother the affairs of the Society detained him in town some time longer. The following letter I had from him on his way to Scotland:

"MY DEAR JOHN,

;

Nottingham, August 6.

"I am much obliged to you for your letter from Penzance, and I am happy to hear so good an account of my mother.

66

Pray address your next letter to me under cover to William Rose, Esq., Clerk to the House of Lords, Melrose, N. B. We are travelling together.

"I shall be very glad to learn what is the temperature of the surface of the water in a deep mine full of water. I wrote to you from Cobham, stating that the Duke of Sormerset has declined the con test for the chair of the R. S. I hardly think that any new claimant will appear.

"I am going to breathe some fresh air upon the moors, and I think I cannot be so near the Tweed without wetting my line in it.

"You probably will be now employed upon your work on the Island of Ceylon. The more you give of personal narrative the better. Men read with pleasure adventures in foreign countries, because it is impossible to anticipate moral circumstances; whereas philosophical principles, and facts depending upon general laws, may be calculated on in all climates. With love to my mother and sisters, "I am, my dear John,

"Many thanks for your letter. Pray endeavour to ascertain the depth of water in the Cornish mines you tried, and the temperature at the surface as it gets colder. This, and the temperature at the bottom, will offer decided evidence as to whether there is any source of heat below. If, for instance, when the atmosphere is 32° there should be a great difference between the temperature of a mine 100

1

feet deep and one 1000 feet deep, the fact would be decisive.

I shall be in town about the 15th October.

Pray address your next letter to me there. As all opposition to my election is at an end, I am in no anxiety to return to London, and I shall take holidays while I may. Pray remember me with all duties and affections to my relations and friends.

"I am, my dear John,

"Very sincerely yours,

"H. DAVY."

The observations which I made on the temperature of mines which had been forsaken, and were full of water, according to my brother's request in this last letter, were rather in opposition to the idea that there is an internal source of heat; and, keeping them in recollection, I cannot help feeling some little doubt relative to the truth of this hypothesis; and to the correctness of what is now generally considered as an established fact, that the temperature of the earth invariably increases with its depth, or from its circumference towards its centre. May it not be asked, in accordance with this view, why are not all springs hot springs? Why is the temperature of water at the bottom of very deep lakes generally, and of the ocean at great depths even within the tropics, about 40° Fahrenheit? Further inquiry may afford answers to such questions not inconsistent with the hypothesis; but, till this inquiry has been made, and the answers given, it may not be amiss to indulge some degree of scepticism on a subject of such great importance in its theoretical bearings, and confessedly enveloped in much mystery.*

* There is a striking passage in Gilbert's posthumous work already referred to, expressing his opinion of the temperature of the earth, when

It was his intention this autumn to have paid his friends in Cornwall a visit. When expecting his arrival at Penzance, I received from him the following letter:

"MY DEAR JOHN,

"Grosvenor Street, Oct. 19.

"I had intended to leave town for Cornwall tomorrow; but I have been caught by an inquiry of the greatest importance, and till I can conclude I cannot stir.

"I have ascertained (repeating some vague experiments of Ersted's) that the voltaic pile is a powerful magnet; i. e. that by the union of the + and electricities, magnetism is produced in the same combinations as heat. I am deeply occupied with this, which promises to explain so much for the theory of the earth do not say anything on the subject. I hope in two or three days to be able to give you the whole details, of which you will immediately perceive the importance. Faraday has discovered a combination of chlorine and charcoal.

"Sir E. Home has made out the use of the pigmentum nigrum. I write from the table where I am magnetising. I rejoice your book is so far advanced.

"If I can conclude my labours by the 24th, I will come down before the session of the R. S. If not,

opposing a notion of that time: Quid tempus perderem probando elementum ignis undique juxta Lunæ sphæram non esse? Contrarium à nulla pendet ratiore, magnoque sensus nostri judicio id falsum esse persuaderi potest. Ut neque altiora à tellure, calidiora leviorave sunt; nam, à superioribus locis nubes et grandies decidunt, frigusque perpetuum est in altissimis montibus, in minus altis minus frigus, qui tamen frigidiores sunt quam planities: et planities convallesque frigidiores sunt interioribus terræ partibus, in quibus nec glacies, nec pruina, sed tepores, calores, etiam et incendia."-Op. Cit. p. 21.