484 
NATURE 
[ Oct. 13, 1870 
cally fallacious. The idea of an engine worked by the ex- 
pansion of nitrogen under the influence of heat was fallacious 
in principle and practically impossible. A gentleman in the 
body of the room said he had listened to the paper with great 
interest, and regretted that it had not been allowed to be con- 
cluded. This remark was received with applause by the audience, 
and still greater applause followed when the author said, in retir- 
ing, that time would show whether the President or the principle 
was right. It seems clear that, having been accepted by the Com- 
mittee of the Section, and the title of it placed upon the programme 
of business, the paper was entitled to be read. We are glad to lay a 
short abstract of the “burked” paper before our readers, express- 
ing no opinion, further than that opinion should not be stifled. 
The principle of the engine is as follows :—Crude nitrogen 
gas is heated in a serpentine system of tubes until the pressure 
is double that of the air, It is then admitted into a cylinder 
in which it presses forward a piston, and is allowed to expand. 
Next it passes into an apparatus where it is cooled, and conse- 
quently diminished to half its bulk. The cooling is effected in 
a new arrangement, which is so constructed that the whole of 
the heat above that of the external air is transferred to an equi- 
valent volume of air passing in an opposite direction. This 
heated air is then used as a blast for the fire, 4‘; going to the 
hearth of the furnace through a tuyere, and 54; mixing with the 
products of combustion immediately above the fire, so as to com- 
plete any imperfect combustion, and also to modify the tempera- 
ture of the whole mass, so that it may not be likely to injure the 
iron of the gas tubes, and the remaining ;% being introduced into 
the System at a point furtheron. The construction of the system 
of tubes is such that, by the time the products of combustion reach 
the open air, they shall have parted with nearly all their heat, and 
transferred it to the nitrogen contained in the tubes, and hence a 
chimney draught cannot be used, and the blast has to be pro- 
duced by a blowing engine. The nitrogen, after having been 
cooled to half the volume it occupied in the first cylinder, is then 
compressed and forced into the system of tubes at the point 
furthest from the fire. It is this forcing the gas back again into 
the system of heating tubes that appears absurd; but it must be 
remembered that the gas while leaving the heating tubes occu- 
pies twice the space it does when being forced back, hence it 
fills a cylinder of twice the area, and the force that may now be 
disposed of is equal to half the pressure exerted in the larger 
cylinder. But the other half of the power is not lest, it is 
simply conveyed back to the heating tube, and is used again. 
The only losses that can arise are those which are incidental to 
all engines, such as radiation, conduction, &c., inasmuch as there 
is avoided the enormous loss of heat that usually goes up the 
chimney, together with the still greater loss that is constantly 
being carried away by the condensed water,—an amount in itself 
six times as great as that converted into work in the steam- 
engine. The inventor considers that he does not expect too 
much if he expects his new heat engine to convert 60 per cent. 
of the heat of combustion into work, a duty that is fully 500 
fer cent. above that of well-constructed steam-engines. 
Of course, as the author was not permitted to finish the 
‘reading of his paper, no discussion was taken upon it. 
REPORTS OF COMMITTEES 
THIRD REPORT OF UNDERGROUND TEMPERATURE COMMITTEE 
Mr. G. J. Symons, whose observations, extending to a depth of 
1,100 feet in a well at Kentish Town, were reported at last 
meeting, has since repeated his observations at several depths. 
The first 210 feet of the well (which is eight feet in diameter 
to the depth of 540 feet) are occupied by air, and in this portion 
of the well the second series of observations give temperatures 
exceeding those observed in the first series by from 2° to 5°, the 
excess diminishing as the depth increases. The second series 
were taken in July and August, whereas the first series were 
taken in January. It is evident thet, in this portion of the well, 
in spite of the precautions taken to exclude atmospheric in- 
fluences, by boarding over the we]l and erecting a hut over it, 
the temperature varies with the seasons, the variations being in 
the same direction as in the external air, but smaller, and dimi- 
nishing as the depth increases, but still amounting to 2°*2 at the 
depth of 2co feet. 
We can feel no certainty that even the mean annual tempera- 
ture in this portion of the well represents the temperature in the 
solid ground. On the contrary, the mean temperature in the 
well at any depth is probably intermediate between the tempera- 
ture of the solid ground at that depth and the mean temperature 
of the external air. 
It is well that such observations should have been carefully 
made and recorded in this ore instance, if only for the sake of 
warning ; and they show that we cannot expect to attain the 
object for which the committee has been appointed by observa- 
tions in large shafts filled with air. 
Mr. Symons has also repeatcd the observations at 250 feet 
(which is 40 feet under water), and at the depths of 600 feet, 
750 feet, and every fifiieth foot from this to 1,100 feet, which is 
the lowest point attainable on account of the mud, which extends 
300 feet lower. The differcnces from the results obtained last 
year are +°2, -°3, —‘4, —‘2, —°2, 0, —‘I, — ‘I, 03 which, 
upon the whole, strongly confirma the correctness of the obser- 
vations. 
The temperature at 1,100 feet is 69 8, which, if we assume the 
mean temperature of the surface of the ground to le He , gives 
wan 
a mean increase downwards of oles of a degree Fahrenheit 
§ 
(55°51) 
i 52°0 | feet. 
The curve in which temperature is the ordinate and depth the 
abscissa, exhibits considerable irregularities till we reach the dep*h 
of 650 feet, beyond which it is nearly a straight line, and repre- 
sents an increase of ‘0187 of a degree per foot. 
The sirata penetrated by the well to the depth to which our 
observations extend, consist of clay, sand, chalk, and marl, be- 
sides flints. (See tabular list appended.) 
Mr. Symons, in his report, calls attention to the anomalous 
position of a column of water, increasing in temperature and, 
consequently, diminishing in specific gravity downwards, and 
suggests the inquiry why the warmer and lighter portions do not 
ascend to the top. The proper reply seems to be that the dimi- 
nution of specific gravity, amounting to less than one part in 
50,000 per vertical foot, does not furnish sufficient force to over- 
come liquid adhesion, and the water is thus able to remain in 
unstable equilibrium. 
Mr. Symons intends during the remainder of the present year, 
verifying those of his observations which have not yet been re- 
peated, and concludes his report by remarking that it appears 
desirable to ascertain by observations from year to year, whether 
the temperature at a given depth (say 1,000 feet) remains con- 
stant or is subject to minute changes, periodical or otherwise— 
a suggestion which appears fully worthy of being carried out. 
Mr. Wm. Bryham, manager of Rosebridge Colliery, Ince, 
near Wigan, has taken very valuable observations during the 
sinking of that colliery, which is now the deepest excavation in 
Great britain. ‘The principal results have already beer given in 
a paper to the Royal Society by Mr. Edward Hull, director of 
the Geological Survey of Ireland, who had previously published 
some important contributions to our knowledge of underground 
temperature, and has now consented to become a member of 
this committee. Some of the depths have however bcen re- 
measured since Mr. Hull’s paper was read, and we aie ow 
enabled, through the kindness of Mr. Bryham, to fumish a 
rather n.ore accurate report. 
The tem} eratures observed, and the depths at which they were 
taken, are as fo}luws :— 
per foot, or 1° for 
Depth in Yares. ‘Temperature Fahrenheit. 
ToD: 5 i : (644 
260)"; . a (¢ 6) 
558 . f 5 ; : 78 
605 . : : 3 z 80 
630 . : c 6 : 83 
663 . z 2 x 85 
C71 £6 
670) % : , : c 87 
724. F * F F 8d2 
745: : : : 89 
761... 5 : : A 903 
WES bot 5 5 : a git 
733. : ; 5 5 92 
soc . : . 5 : 93 
$06 . ‘ < < 934 
S15). 5 ; : 5 4 
All these temperatures, except the two first, were observed 
during the sinking of the shaft, by drilling a hole with water, 
to the depth of a yard, in the solid strata at the bottom. A 
ainda 
