The Constituents of the North Lancashire Flora, Yorks. Nat. Union

Bibliography: Freshwater Algæ, 1888 to 1892.
The Oak beside the River at Ashiesteel

Further Notes on the Mycetozoa, with a List of Herts N. H. Soc.

Species from Herts, Beds, and Bucks
List of some Rarer Berwickshire Plants

Berwicksh. Nat. Club
Yorks. Nat. Union.

Report of the Botanical and Microscopical Burt. N. H. Arch. Soc.
Section, 1892-93

Underground Temperature - Twenty-first Report of the Committee, consisting of Professor J. D. EVERETT (Chairman and Secretary), LORD KELVIN, Mr. G. J. SYMONS, Sir A. GEIKIE, Mr. J. GLAISHER, Professor E. HULL, Professor J. PRESTWICH, Dr. C. LE NEVEFOSTER, Professor A. S. HERSCHEL, Professor G. A. LEBOUR. Mr. A. B. WYNNE, Mr. W. GALLOWAY, Mr. JOSEPH DICKINSON, Mr. G. F. DEACON, Mr. E. WETHERED, Mr. A. STRAHAN, and Professor MICHIE SMITH. (Drawn up by Professor EVERETT.)

INFORMATION as to underground temperature in the southern hemisphere has hitherto been very scanty. Importance therefore attaches to observations which have recently been taken in a deep bore in New South Wales by T. W. Edgeworth David, Professor of Geology in Sydney University, and E. F. Pittman, Government Geologist. The following account is derived from a paper by these gentlemen to the Royal Society of N.S.W., read December 6, 1893, supplemented by letters from Professor David to the Secretary of the Committee.

The bore is 2,929 ft. deep, and is the second of two which have been sunk at Cremorne on the shores of Port Jackson.

A protected maximum thermometer had been furnished by the secretary to Professor David when he went out to Sydney in 1882; but it had passed through several hands, and was not forthcoming when the opportunity for observation occurred. Professor David had accordingly to avail himself of such instruments as were accessible, and he borrowed four maximum thermometers, including two inverted Negretti's belonging to Mr. H. C. Russell, the Government Astronomer, which had Kew certificates. They were similar in pattern to those adopted by the Committee, except that there was no outer glass-case. In place of this, 'a strong piece of wrought iron water-pipe, about two feet three inches in length,' was employed. A cap-piece was sweated on to the lower end of this tube, the threads of the screw in the cap-piece and pipe being filled with molten solder, and the cap-piece being screwed on while the solder was still molten The lower end of the pipe was then filled to a depth of about two inches with brass turnings. The thermometers were next carefully lowered into the tube.' They had their bulbs uppermost, as usual. Brass turnings were then packed around them in order that the heat might be conducted rapidly to their bulbs from the water in the bore. Strings were fastened to the bulbs to facilitate the withdrawal of the thermometers from the tube after the experiment of taking the temperature had been completed. The ends of these strings were carried close up to the top of the pipe, the brass turnings being packed around them like tamping around a fuse in a shot-hole. A few cardboard wads and a layer of loose paper two inches in thickness were inserted in the upper portion of the tube, to prevent the conduction downwards of the artificial heat, which would otherwise travel down to the thermometers from the upper end of the tube when it was dipped in the molten solder, previous to the upper cap-piece being sweated on. A ring-bolt for attaching the lowering cord was screwed into the upper cap-piece, with molten solder sweated into it; and the whole cap-piece was then screwed and sweated on to the upper end of the tube in the same manner as the lower cap-piece.'

The first experiment was a failure, the thermometers, though left for about an hour near the bottom of the bore, indicating about the same temperature that they had before lowering. This failure is attributed either to the non-conducting action of a few thicknesses of soft paper in which the bulbs were wrapped, or to the mercury which had left the bulbs having returned to them again while the tube was being conveyed from the bore to the plumber's shop, where the cap-piece was removed.

In the second experiment 'no paper was wrapped round the bulbs, but the brass dust was continuous from the bulbs to the sides of the iron pipe.' At the depth of 2,733 ft. an obstruction was encountered which prevented the tube from going lower, and which also caused the suspending wire to kink and break. After an immersion of about twenty-seven hours, the wire was successfully grappled, and the tube brought to the surface. 'The upper cap-piece was then rapidly heated in a chafing dish of charcoal made of an old nail-can, with a hole cut out of the bottom just sufficiently large to admit of the upper end of the tube being passed up it, and oxygen gas from a compressed cylinder was blown through a Fletcher's blowpipe on to the charcoal, so that in less than half a minute the solder in the threads of the cap-piece was melted; the lower portion of the tube containing the thermometers being meanwhile wrapped in wet cloths to prevent the heat travelling downwards. The cap-piece having been unscrewed and the thermometers withdrawn, the highest temperature registered was found to be 97° F.' 'Not a drop of water had found its way into the tube.'

On the following day the experiment was repeated, no wire being used for lowering, but only tarred rope; and sheet lead was wrapped round the tube to increase the weight. The tube was left down for one hour, and the maximum temperature registered was 96° F. The difference of 1° below the former observation is what might fairly be expected from the stirring of the water and the thermal capacity of the sheet lead which, with the tube, weighed 30 lb. The first result, 97° F., is therefore adopted as the true temperature at the depth of 2,733 ft. The mean surface temperature, as determined by Mr. H. C. Russell, is 63° F., giving an increase of 34° in 2,733 ft., which is at the rate of 1° F. for 80 ft.

As regards the possibility of disturbance of temperature by convection, Professor David mentions in a letter to the Secretary that the bore was only four inches in diameter. He also says, 'You understand, of course, that we can do nothing in the way of taking temperatures in a diamonddrill bore until the bore is quite completed, owing to the chilling of the rock at the sides of the borehole by the cold water which is being constantly forced to circulate under pressure through the bore.'

The temperature of the water of Port Jackson at the greatest depths near Cremorne, varying from 45 to 63 ft., was found (on December 6, 1893) to be uniform at 68° F. As this temperature is higher than that of the ground at the same level, no cooling effect can be attributed to the water. The slow rate of 1° F. per 80 ft., deduced from the observations, would therefore appear to be a good approximation to the truth.

It is expected that shafts will shortly be sunk at Cremorne, and will afford opportunity for the systematic observation of rock temperatures from the surface to a depth of nearly 3,000 ft. The first 1,000 ft. will be in horizontally bedded sandstone, and the remainder chiefly in clay shales, with interstratified sandstones and conglomerates.' The observations will be taken by Professor David and Mr. Pittman, with the