Oct. 31, 1872 



NA 1 VRE 



54^ 



the assumption that a constant power is being exerted during 

 the stated period capable of developing, as at present, 

 the stupendous energy of 240 millions of foot-pounds in 

 a single minute, for each square foot of the surface of a sphere 

 whose diameter exceeds 850,000 miles. This inconceivable 

 amount of work cannot be performed with a less expenditure 

 than the motive energy developed by the fall of a mass equal to 

 the mass contained in the sun, the weight of which is nearly a 

 thousand times greater than the weight of all the planets of the 

 system. Obviously a continuous development of such an amount 

 of energy is physically impossible, since there is a limit to the 

 distance through which the weight can fall. Now the foregoing 

 demonstration enables us to determine the said limit, with 

 suflicient exactness to prove that although the efficiency of the 

 great motor, during the past, may be measured by hundreds of 

 millions of years, its future efficiency will be of comparatively 

 brief duration. 



Statements relating to the permanency of solar heat, based on 

 the assumption that no diminution has been observed during 

 historic times, have no weight in view of our demonstration 

 showing that a shrinking of ^V of the sun's diameter can only 

 reduce the intensity from Sl° to67°'3, difference = I3"S, in the 

 course of two millions of years. This period being 500 times 

 longer than " historic times " say 4,000 years, it will be seen that 

 the diminution of the temperature produced by solar radiation, 



has not exceeded •' - = 0'027, or — deg. Fah. since the 



500 37 



erection of the Pyramids. 



It will be proper to observe, before concluding oui brief 

 investigation of the source of solar energy, that, the development 

 of heat by the shrinking of the sun, however fully demonstrated, 

 leaves the important question unanswered : how is the heat 

 generated by gravitation within the mass transmitted to the 

 surface ? If the matter within the sun is a perfect conductor 

 of heat— a very improbable supposition — that fact alone 

 furnishes a satisfactory answer. Imperfect conductivity, on 

 the other hand, calls for other means of transmitting 

 the energy from within, to make good the enormous loss 

 caused by the external radiation. Besides, the falling of the 

 crust at the rate of ten feet per month, attended by increase of 

 internal pressure, and probably ejection of gaseous matter, to- 

 gether with the disturbance occasioned by contraction at the sur- 

 face, disclose a mechanism of startling perplexity. But the parting 

 with 312,000 thermal units for each square foot of the solar sur- 

 face, involving an expenditure of kinetic energy fully 240,000,000 

 ioot-pounds per minute, cannot be made good in that brief space 

 of time, unless the sun shrinks at the rate ascertained by our cal- 

 culations. 



The development of solar energy in accordance with the com- 

 bustion hypothesis (lately resuscitated by M. E. Vicaire) merits 

 no consideration, while careful investigation has proved the 

 meteoric hypothesis to be untenable. It must be admitted, how- 

 ever, that the mechanical difficulties alluded to, especially those 

 relating to the means of transmitting the heat to the surface of 

 the sun, any temporary local derangement of which must be pro- 

 ductive of dark spots for a time, are of such a nature that the 

 absolute certainty of solar radiation may be questioned ; nor is 

 evidence wanting to show that the solar mechanism is liable to 

 derangement. History informs us that the great luminary has, 

 during several seasons, partially failed to perform its functions. 

 Herschel states, in his " Outlines of Astronomy," that " in the 

 annals of the year A.D. 536 the sun is said to have suffered a 

 great diminution of light, which continued fourteen months. 

 r"rom October A.D. 626 to the following June a defalcation of 

 light to the extent of one-half is recorded; and in a.d. 1547, 

 during three days, the sun is said to have been so darkened that 

 stars were seen in the day-time. " Again, the glacial periods, the 

 ascertained abrupt termination and recurrence of which puzzles 

 the geologist, point to periodical derangement of the solar me- 

 chanism in past ages. J. Ericsson 



EXTRAORDINARY WHIRLWIND IN 

 IRELAND 



IN a letter to the Belfast News-Letter, Mr. C. J. Webb 

 describes an extraordinary whirlwind which occurred 

 in the district around Randalstown, about six miles N.W. 

 of Antrim, near the shoree of Lough Neagh, on the asth 



of August last. The same phenomenon was witnessed 

 about an hour and a half earlier the same evoning at 

 Banbridge, about seven miles S.W. of Dromore. It was 

 first seen near Randalstown about 5 P.M., between that 

 place and Toome, moving rapidly up Lough Neagh from 

 the south, and presenting the appearance of a defined 

 column of spray and clouds, whirling round and round, 

 and not many yards in breadth, while at its base the water 

 was lashed into a circle of white foam. It was next 

 heard of in the neighbourhood of Staffordstown, about a 

 mile from the lake, where it partially unroofed two houses, 

 and damaged any trees or crops which happened to be in 

 its course. From this point it travelled in a straight line 

 for Randalstown, about three miles distant. It passed 

 across a field close to Mr. Webb's house, levelling eight 

 haystacks, and carried a considerable part of the hay up 

 into the air out of sight. The breadth of the storm 

 could be accurately ascertained at this point, and must 

 have extended about thirty yards, as stacks remained un- 

 ruffled at either side, while those between were thrown 

 down and carried away or scattered about. Everything 

 it lapped up was whirled round and round, and carried 

 upwards in the centre, while dense clouds seemed to be 

 sucked down on the outside, and came close to the earth. 

 Both before and after there was lightning and incessant 

 peals of thunder ; but there was no rain till some time 

 afterwards. Mr. Webb next observed its track in a hol- 

 low, some three hundred yards further on, where it 

 knocked down a haystack, and then plunged into a wood 

 of fine old Irish oaks. Here it tore numerous branches and 

 limbs from the trees, carrying some along with it, and 

 throwing others to the ground. One noble tree in the 

 centre of the wood seems to have been a peculiar mark 

 for its vengeance, although it would have been completely 

 protected from any ordinary storm, owing to its position. 

 It next passed across a corner of Shane's Castle demesne. 

 Some who were at a short distance from this point describe 

 its approach as causing considerable alarm. It was ac- 

 companied by a wild rushing noise, and the crashing of 

 the trees and branches could be heard becoming louder 

 and louder as it advanced. It crossed the valley over the 

 railway viaduct, close to Randalstown, fortunately avoid- 

 ing the village. It here presented the appearance of a 

 vast whirling column of leaves and branches, mingled 

 with clouds which looked like smoke. 



The railway station next suffered, innumerable slates 

 and two and a half cwt. of lead being torn from the roof 

 in an instant. A great part of the railings surrounding 

 the gardens was torn up, and an iron bar one inch thick, 

 belonging to the gate, was bent to an angle of sixty de- 

 grees. A small shed at the rear of the station was unroofed, 

 rafters and slates being hurled to the ground. What will 

 give some idea of the excessive pressure of the wind, is the 

 fact that three boards of the flooring of the waiting-room 

 were forced up, owing to the wind finding an entrance to 

 a cellar underneath, though the only apertiwe was a round 

 hole about one foot in diameter. All this was the work of 

 a few moments. The storm then passed away, leaving 

 comparative calm behind. It next crossed an adjacent 

 bog, scattering the turf in all directions. The last place 

 Mr. Webb heard of its having visited was a farm house 

 about three miles from R.indalstown, between Antrim and 

 Ballymena. It would be interesting to ascertain whether 

 it travelled across to the searcoast. 



NOTES 



The British Association Committee on Mathematical Tables, 

 of which Prof. Cayley is the chairman, has determined to tabu- 

 late the Elliptic Functions, or more accurately, the Jacobian 

 Theta Functions, which are the numerators and denominators 

 of the former, and their logarithms. The tables, which are of 

 double entry, will therefore give eight tabular results for each 



