NA TURE 



[May 3, 1894 



On Iron Crows' Nests. 



Three years ago, the removal of an old tree in the Cossipore 

 Ordnance Factory, near Calcutta, brought to light a singular bird's 

 nss;,composednninlyof bent and twisted fragments of stout iron 

 wire, such as is used to bind up bunlles of bar iron for trans- 

 port. The pieces, which were all about as thick as stout tele- 

 graph wire, were of considerable lengih and weight, and were 

 keyed together by their own irregularities ; but as there was no 

 e»'idence by which to identify the builder, I merely made a note 

 of the circumstances. 



Last year, however, attracted by the laboured flight of a crow 

 carrying in its bill a very unwieldy and apparently heavy load, 

 I watched the bird until, frightened by a pissing object when 

 about two feet from the ground, it dropped its burden, which I 

 at once secured. I found it to be a piece of crumpled iron wire, 

 which on measurement in my laboratory proved to be 23! 

 inches long between its apparent extremities (straightened 

 out it measured 35* inches in length), to have a diameter of o"i25 

 inches ( = No. 11 B. W.G.), and to weigh 5572 grammes, or 

 nearly 861 grains. The bird was in the main road, about 300 

 yards from the silc of the original nest. 



This evidence as to the ownership of the nest, and of the 

 weight which an Indian crow can carry, may perhaps interest 

 some of your readers. Walter G. McMillan. 



Mason College, Birmingham, .'Vpril 20. 



Early Arrival of Birds. 



Mr. Prideaux, in the last issue of Nature, having 

 recorded the unusually early arrival of the summer migrants 

 in Surrey, it may perhaps be permissible to state the date of 

 arrival here. The cuckoo, uttering its festive note, flew into 

 a tree in. my garden on March 25, attracting the attention of 

 the whole household, and has been heard at intervals in the 

 neighbourhood of Worcester ever since. The swallow and 

 margin were here on the 4'.h inst., the willow warbler and the 

 white-throat on the 7th, and the red-start on the l6th. 

 Nidificalion was remarkably early this season. In my garden 

 the long thrush, blackbird, and robin hatched out by March 30, 

 and the missal thrush in an orchard close by was, .is usual, 

 earlier in its family arrangements. I heard the swift on the 

 26th inst. The spring flora was also early : lilac, hawthorn, 

 bluebell, cowslip, primrose, wood anemone, spotted orchis, and 

 orchis morio were in blossom on the 2o:h inst. ; the sweet violet 

 gone, and the dog violet blooming profusely in its place. 



There is nothing wonderful in the cuckoo being here in 

 March. The wonder is that it was then vocal. 



J. Lloyd Bozward. 



Henwick, Worcester. April 28. 



Irritability of Plants. 



I.N your issue for April 19 (vol. xlix. p. 586 ) there is a short 

 notice of a paper by Pr.jf. Pfeffer on the " Irritability of Plants." 

 In it yon say : " Pfeffer inslnnces the remarkable researches of 

 Hegler on the effect of mechanical traction on growth slems, 

 which when stretched by a weight, gain mechanical strength 

 through the devel.'pment of the mechanical tissues, which 

 followt as a response to the pull to which they are sub- 

 jected." 



Thi< recalls to mind the interesting passage in Tennyson's 

 " Idylls of the King" : 





Derby, April ..( 



'li-M 

 fly -itr, .inil (tpt 



R. M. Di;elev. 



placed at some distance, and connected to the microscope by a 

 curved glass rod, which conveyed the light by internal reflection. 

 Incandescent lamps might be used in a similar manner, 

 and some means could be devised in order to intercept the heat 

 they produce,' if it be objectionable. 



.\ few days ago I noticed an article on Dr. Phillips' electric 

 lamps, which he has employed to light the mouth, and the cavities 

 between the mouth and the nose, and you recently published a 

 paper read before the Royal Society, by Prof. H. M. Ward, on 

 the bactericidal action of light, which partly confirms my 

 views. It seems worth while, therefore, to make experi- 

 ments with arc rays projected indirectly as above, and 

 with incandescent lamps, and that especially upon diphtheria 

 membranes. J. Erede. 



Rome, April iS. 



Centipedes and their 'ifoung. 



I.s No. 1275 of Nature (vol. xlix. p. 531), Mr. Urich, of 

 the Trinidad Field Naturalists' Club, asks for information about 

 the breeding habits of centipedes. 



.Similar observations to those made by the members of the 

 Trinidad Club, and described by .Mr. Urich, have been pub- 

 lished by Kohlrausch (" Beitrage ziir Kenntniss der Scalapen- 

 driden." Diss, Marburg, 187S), and these are referred to in the 

 standard work on Myriapoda by Latzel ("Die Myriapoden der 

 O-terreichiich-Ungarischen Monarchic.'" Wien, 1S80, p. I36'. 

 and also in the " Lehrbuch der nerglischenden Entwicklungs- 

 geschichle '' Jena, 1890), by Korschelt and Heider, p. 725. 



Czernowitz, April 25. R. v. Lexdenfeld. 



The Action of Light on the Diphtheria Bacteriuin. 



Some lime ago it was reported that colonies of the diph- 

 theria bacterium do not thrive well when ex; '■ '.:ht, andit 

 occurred to me that the electric light n. .1 means 



of checking the development of the f.\! _ ...,:.. r.ines by 

 projecting a very powerful arc light on the throat, for it 

 ii known that the tiuuo arc to some extent penetrated by 

 tight. Or poiMlily the arc light could be sent into the 

 throat through the mouth? 1 know that in Germany 

 Diicroicopic object* have been lighted with the aid of a lamp 



NO 1279. VOL. 50] 



Marsupites in the Isle of Wight. 



I,N a recent visit to the Isle of Wight, plates of MarsHf'i:^ 

 were found by Mr. R. M. Brydone and myself at Freshwater. 



The locality is one in which these fossils might be expected 

 to occur, but so far as I know they have not been recorded 

 hitherto from any part of the island ; certainly not by Barrois, 

 nor in the last edition of the " Survey Memoir." 



Winchester College. C. GRIFFITH. 



POINCARE ON MAXWELL AND HERTZ> 



AT the time when Fresnel's experiments compelled all 

 researchers to admit that light is due to the vibra- 

 tions of a very subtile fluid tilling the interplanetary 

 spaces, the researches of Ampere made known the mutual 

 actions of currents, and founded electrodynamics. 



But one step more was required to suppose that this 

 same fluid, the ether, which is the cause of luminous 

 phenomena, is at the same time the vehicle of electrical 

 actions. This step Ampere's imagination enabled him 

 to take ; but the illustrious physicist, while announc- 

 ing this sedactive hypothesis, did not see that it was so 

 soon to take a more precise form, and receive the begin- 

 ning of its confirmation. 



It was still, however, but a dream without consistence, 

 till the day when electric measures indicated an un- 

 expected fact — a fact recalled by M. Cornu in the last 

 Annuaire, at the end of his brilliant article devoted to 

 the definition of electric units. To pass from the system 

 of electrostatic units to the system of electrodynamic 

 units, a certain transformation-factor is employed, the 

 definition of which I will not recall, as it is to be found 

 in M. Cornu's article. This factor, which is also 

 called the ratio of unities, is precisely equal to the velocity 

 of light. 



The observations soon became so precise that it was 

 impossible to attribute this concordance to chance. One 

 could not doubt therefore that there were certain intimate 

 relations between the optic and the electric phenomena. 

 But the nature of these relations would perhaps still 

 have escaped us if Maxwell's genius had not guessed it. 



> Tran^Lition of an article by M. PoincarO, in ihc Annuain- of the 

 Bureau de« Longitudes for 1891. 



