Augusi 19, 1880] 



NATURE 



?,6' 



Charleraont. Facing the house, a stone's throw or two in front 

 of the lawn, was a river called the Tall, which ran into the close- 

 at-hand Callan, which again ran into the Black Water, which, 

 in turn, emptied itself into that immense puddle which bears the 

 name of Lough Neagh. The waters of Lough Neagh, unable, 

 by reason of the obitructions in the Lower Bann, to escape 

 rapidly enough into the sea, swell up and cause backwater in the 

 rivers I have named, and others as well. The result is the 

 periodic flooding of thousands and tens of thousands of acres of 

 valuable land, to the immense prejudice of the occupants and 

 country at large. The Tall, I should observe, was banked or 

 dyked up on both sides. In some places, however, the dyke 

 had given way, so that at flood-time — and it was flood-time at the 

 period I speak of — the waters of the Tall were awash w ith those 

 of the flooded meads on both sides. There was further a 

 rapid current in the Tall, and before it merged into the Callan 

 the stream had to pass under the arch of a bridge which it filled 

 to the crown. In fact the battlements themselves were nearly 

 covered, and the country, as far as the eye could reach from the 

 position which I at the moment occupied at the foot of the 

 lawn, wore the aspect of a sea. At this precise juncture two 

 horses, whilom occupants, I presume, of the then flooded meads, 

 were to be seen slowly wading in the direction of the Tall. The 

 green summit of the dyke was for the most part visible, and 

 upon this the poor brutes mounted, in quest, I suppose, of some 

 outlet. They had not gone very far when, owing to the trea- 

 cherous footing, one of the horses lost his balance and fell, 

 rolling over and over into the Tall. He swam on bravely, the 

 other horse stretching down at intervals a sympathising muzzle, 

 making indeed repeated efforts to escape, but falling back each 

 time into the surging current. I was alone, surveying the 

 transaction, from which I never removed my eyes, with the 

 deepest interest. All at once the horse that w-as on the dyke, 

 keeping pace at a sort of half-trot with the other, burst into a 

 hand-gallop, and when he had got sufficiently beyond his 

 struggling comrade, bounded himself into the Tall. Swimming 

 briskly onwards for a few fathoms, he then made his way out 

 through what he must have seen beforehand was a practicable 

 breach in the dyke, followed on the instant by his friend, evad- 

 ing, not a moment too soon, the submerged bridge, w here they 

 would have otherwise inevitably gone under. So long as my 

 eyes could follow them they dashed onwards at a gallop, throw- 

 ing up their exultant heels and flourishing their tails across the 

 flooded meadows. It is now many years since I beheld this 

 astonishing spectacle, which my memory recalls as freshly as if 

 it had happened yesterday, awakening, as I think it is well 

 calculated to do, serious reflections in regard of our mysterious 

 associates and the wondrous Power which has called them into 

 being, and now sustains them and ourselves alike in this transi- 

 tory state which we term life. Henry MacCormac 

 Belfast, August 



Radiation. — A Query 



In Baily's experiments with the torsion-rod and two leaden 

 balls weighing 3Soi pounds each, it was found that the radiation 

 of heat from the leaden masses affected the vibrations of the 

 torsion-rod. These masses were thereupon gilded, and the 

 torsion-rod protected by a gilt box covered with thick flannel, 

 and the disturbing influence overcome. How did radiation 

 affect the motion of the torsion-rod? F. G. S. 



"On a Mode-of Explaining the Transverse Vibrations 

 of Light" — The Expression "Radiant Matter" 



WiTHOtTT wishing at all to underrate the apparent difficulty 

 noticed by your New Zealand correspondent, Mr. J. W. Frank- 

 land (Nati;re, vol. xxii. p. 317) in regard to my paper under 

 the above heading (NATtJRE, vol. xxi. p. 256), as it would be 

 against the interests of truth to do so ; I may nevertheless call 

 his attention to a letter of mine (Nature, vol. xxi. p. 369), 

 where an attempt is made to meet the difliculty in question. 

 The point is to account for the circumstance (admitting that it is 

 rendered necessary by physical evidence) that the velocity of 

 propagation of gravity must, at least, be very much greater than 

 that of light. I will merely confine myself here to recapitulating 

 one of the main conclusions in a somewhat different form, viz., 

 it appears to be necessary to look to a separate medium for 

 gravity, or '(more accurately) to one medium with particles of 

 two grades of dimensions ; the one set of particles having very 



minute mass, and consequently enormous velocity, and concerned 

 in the effects of gravity ; the other set, of much greater mass and 

 slower velocity, concerned in the phenomena of light. It will, I 

 think, be so far tolerably evident that if the number of the more 

 minute set of particles be comparatively very great, the pressure 

 produced by them would be correspondingly great, and therefore 

 these particles would be mainly (i.e., almost exclusively, if their 

 number were sufficiently great) ^ concerned in producing gravity. 

 On the other hand, on account of the extreme velocity of these 

 particles, they could not apparently be appreciably concerned in 

 the phenomena of light, since the molecules of gross matter 

 would vibrate among them without appreciable resistance. For 

 it is a well-kno^Ti dynamical fact that the resistance opposed to 

 the motion of a body in a medium diminis/ies as the velocity of 

 the particles of the medium increases. It may be worth observing 

 perhaps that this idea of three grades of dimensions in matter 

 (viz. gross matter, light-carrying matter, and gravific matter) 

 appears to be an old one. Thus a book was published in 1827 

 by Dr. Blair, formerly Regius Professor of Astronomy in the 

 University of Edinburgh, entitled "Scientific Aphorisms" (to 

 which my attention was called by Prof. Tait), where the idea of 

 three grades of dimensions in matter is set forth, and a theory of 

 gravity very similar to that of Le Sage expounded. Also RI. 

 Prevost ("Deux Traites de Physique mecanique") expresses, I 

 believe, the view that matter exists fundamentally in three grades 

 of magnitude. 



It may be rather a curious fact to notice that if the theory, that 

 the Kther consists merely of finely subdivided matter in .the 

 ultra-gaseous state, light being regarded as a vector property 

 carried off by the atoms in their passage through the open 

 structure of the vibrating molecules of gross matter, as suggested 

 by the late Prof. Clerk Maxwell, article " /Ether," new edition 

 of the " Encyclopa;dia Britannica" (i.e., with range of free path 

 greater than planetary distance. Nature, vol. xxi. p. 256),- should 

 ultimately turn out to be substantially true ; then the term "radiant 

 matter," employed by Mr. Crookes in connection with his 

 experimental researches, would have its practical application in 

 nature on a large scale — or light would be actually propagated 

 by "radiant matter." If, on an examination of the theory in 

 that spirit of good-humoured impartiality representing entire 

 freedom from the predilections of any school of thought (the 

 best guarantee of truth) — the difficulties attaching to it should 

 not be considered insurmountable ; then it may be worth re- 

 marking that the theory, without violating in the least the 

 essential principles of the firmly-established undulatoiy theory, 

 contains nevertheless (in its corpuscular essence) one of the ideas 

 of Newton ; so that it would appear that the latter might not 

 have been entirely wrong, nor the upholders of the opposite 

 view completely right, but that a partial reconciliation of their 

 rival ideas might be possible. S. ToLVER Preston 



London, August 10 



Earthquake in Smyrna 



Accounts are freely coming forward, but they are of popular 

 interest, seismological details being scanty. I m,ust premise 

 that in in 1862 I took great interest in promoting Abyssinian 

 wells in Smyrna, and that large numbers were put down. When 

 the French Company built the quay the new works there were 

 similarly supplied, and the result has been that for some years 

 the surface and pipe-wells in the p.irallel Marina and Frank 

 Streets have been wanting in water. 



Within a few hours after the earthquake it was noticed that 

 both classes of wells, say 600 feet from the sea, were freely 

 supplied with water. This fact appears to me deserving of 

 record. 



It is said that the earthquake was most felt near the Greek 

 Cathedral of St. Photius, at the Three Corners in Frank Street. 

 It was here the ground opened in the last century earthquake 

 and swallowed up two men, as I heard by tradition ; and I 

 always walked across the churchyard in full remembrance. 



Of late years some kind of a landslip took place on Mount 

 Fagus, or the Castle Hill, where Alexander the Great fell asleep. 



' It may be wortli noting in connection with this that (.iccording to a 

 principle developed by Sir W. Thomson, Phil. Ma^., May, 1873) it appears 

 that if the "elastic rigidity" of the /<i>iv>-part:cles were such that they 

 suffered no appreciable diminution of velocity at rebound from gross matter, 

 they would not be appreciably concerned in the effects of gravity (even if 

 their number were comparable to that of the smaller set of particles). 



^ Also previous papers by the present writer (on the same subject)— /'/i//. 

 Mitff., September and November, 1S77, February, 1878, April and May, 



