270 



NA TURE 



[July iS, 1895 



would cause an augmentation of its angular velocity around 

 the sun. The period of revolution would take less lime, and the 

 length of the year would gradually decrease. Observation 

 proves that this is not the case, and the necessary conclusion is, 

 that there is no resisting medium in space, which must be, there- 

 fore, considered as perfectly void. 



There is no objection to be made to this reasoning so long as 

 we suppose the sun immovable in space, which was the gener- 

 ally accepted belief in Newton s time. But we know at present 

 that the sun, with all the planets, has a motion through 

 space ; and this knowledge changes the conditions of the 

 problem, as may be demonstrated by what lollows. 



In theaccompan)-ing figure, s is the sun in a certain |x>int of its 

 orbit in space, t: is the earth in a certain |x>int of its orbit around 

 the sun. I^t the linear velocity of the sun in its orbit Iw v, and 

 the linear velocity of the earth in its own orbit be v. 



When the earth is on one side of the sun's orbit, say in E, 

 then V and v are opposite in direction, and the absolute velocity 

 of the earth in sjaace will Iw v-<'. When the earth is on the 

 other side of the sun's orbit, say in c, then v and v have the 

 same direction, and the absolute velocity of the earth will be 

 V -f- V. 



Now it seems evident that we have here what may l>e 

 called a self-acting regulation of the angular velocity of the 

 earth in its orbit around the sun. For the absolute linear 

 velocity of the earth is jwriodically accelerated and retarded, 

 and the mean velocity would remain exactly constant if the sun's 

 orbit were a straight line. 



.Most prolably the sun's orbit through sjrace will prove to be 

 a curve. If this is the case, then the part of the earth's orbit on 



the concave or outer side of the sun's orbit will \)e somewhat 

 longer than the part on the convex or inner side. 



If this l)e so, then the acceleration on the outside part will l>e 

 somewhat greater than the retardation on the inner side of the 

 earth's orbit. Thus the surplus velocity, gained in each revolution 

 around the sun, will compensate the loss of linear velocity which 

 the earth might suffer in its yearly orbit around the sun by the 

 resistance of a sup|xised mediuni in s|)ace. 



It might, however, be askeil. Why it is that this compensa- 

 tion is s<j exact as we find it to lie ? For I^placc, in his well- 

 known work on the " .Systeme du nionde," explains clearly 

 that no change in the |>enod of revolution uf the earth around 

 the sun has been obser^'ed. 



But we may quite iis well wonder why the tem|>cralure of our 

 bkxKl is nearly constant ; and the Ijesl answer to such questions 

 is in the well-known words : " Philosophy does not ask what 

 agrees, but what is." 



The sun's motion in space is a iliscovery with far-reaching 

 consequences for science in general ; and if space be allowed, a 

 few other corollaries must follow upon it. For the present, it is 

 better to limit research to the single question as to whether 

 we may a<lmit the existence of a resisting medium in s|)ace. 

 The answer is that the di.scovcry of the sun's motion in sixice 

 allows us to settle this much disturl>ed tjucstion in a )X)Silive 

 sense. 



This result h.is a |xirticular value, Iwcause it takes away the con- 

 tradiction Iwiwcen Iwr. theories which are Ixith generally ailniitled. 

 Till- iirwliil.iioty ilR<iry of light, which was first enuncialerl by 

 llu)j;iii-. viii.|-.,.s the existence of an elastic meiliuni in s|Kice. 

 When It IS dcfiionslrated lliat the sup|y>sition of this medium 

 is not incom|>alible with Newton's theory of central forces as 

 applied lonur planetary sv. I. rn, il.l, imisi irrMJiily be considered 

 »» a step in advance. .\. lliET. 



Delll, Holland. Jul) ; 



NO. 1342, VOL. 52] 



THE I.XTERXATIOyAL CATALOGUE OF 

 SCIENTIFIC PAPERS. 



'X'HE following report of the Inteinational Catalogue 

 ^ Coiiiinittce was presented to the President and 

 Council of the Royal Society on July 5, and the recom- 

 mendations contained in it were approved. 



-At the first meeting of this Committee (February 8, 

 1894), the .Memorial to the President and Council (July 

 1893) which led to the appointment of the Committee, and 

 the Minute of Council of December 7, 1893, appoint- 

 ing the Committee, lia\ iny been read, it was resolved to 

 request the President and Council to authorise the 

 Committee to enter directly into communication with 

 societies, institutions, &c., in this country and abroad, 

 with reference to the preparation, by international co- 

 operation, of complete subject and authors" catalogues of 

 scientific literature. 



Subsequently, a draft circular letter was prepared, 

 which, on February 22, 1894, received the approval of 

 the President and Council, who also authorised its issue. 



This letter was sent to 207 societies and institutions 

 selected from the exchange list of the Royal Society, and 

 to a few others. It was also sent to the Directors of a 

 number of Observatories and of Ciovernment geological 

 surveys, to the Foreign .Members of the Royal Society, 

 as well as to those of the following .Societies : — Chemical, 

 (ieological. Physical, Royal .\stronomical, Linnean, 

 Royal Microscopical, Entomological, Zoological, Physio- 

 logical, and Mineralogical, and of the .-Anthropological 

 Institute. .\ special letter was addressed to the Smith- 

 sonian Institution. 



More than a hundred replies to the letter have been 

 received ; several of these are reports of Committees 

 specially appointed to consider the suggestions put 

 forward by the Royal Society. .\ list of answers received 

 up to December 1894, with brief excerpts from the more 

 suggestive, was issued to members of the Committee early 

 in this year. It should, however, be added that from 

 some important institutions no answer has as yet been 

 received. 



It may be said at the outset that in no single case is 

 any doubt expressed as to the extreme value of the work 

 contcni|)l:itcd, and that only two or three correspondents 

 question whether it be possible to carry out such a work. 

 It is a great gratification to the Committee that the 

 matter has been taken up in a most cordial manner by the 

 .Smithsonian Institution, the .Secretary of which, in his 

 reply, refers to the desirability of a catalogue of the kind 

 suggested as being so obvious that the work commends 

 itself at once. The importance of having complete sub- 

 ject catalogues, and not mere transcripts of titles, is also 

 generally recognised. 



Some bodies and indi\ iduals take the m.itler up very 

 warmly and urge th.it steps be taken forthwith to put the 

 scheme into action, this being especially true of the 

 replies received from the United .States ; others, while 

 giving a general approval, dwell upon the difficulties of 

 carrying out the suggestions put forward ; and others, 

 again, ask for more tlctails before committini,' them- 

 selves to any answer which may seem to entail future 

 responsibility, especially of a linancial character. 



Incidentally it may be pointed out as very noteworthy 

 that over and over ag.iin reference is m.ide to the great 

 value of the Royal Society's "Catalogue of .Scientific 

 Papers." There is abundant evidence that considerable 

 use is made of this on the ccmtinent of Kurope. .And it is 

 clear that a proposal to carry out a more comprehensive 

 scheine initially under the direction of the Royal Society 

 of London is likely to meet with general approval owing 

 to the fact that the Society is credited with having 

 already carried out the inost comprehensive work of the 

 kind yet attempted. Indeed, the Academy of Natural 

 Sciences of Phil.adelphia, U.S..A., directly advticates the 



