152 



NATURE 



[December 14, 1899 



suggested and the methods proposed, at certain periods of the 

 year over the area prescribed, also biological plankton investi- 

 gations similarly. What extra expense this will be to the 

 Board it is not for me to say ; but with its staff and knowledge 

 of the methods to be employed, the experience and equipment 

 it has at its command, this will not be anything very great. 

 There is no necessity here for co-ordinating, first of all, the work 

 that might be done at St. Andrews, Millport, and Granton. These 

 places will carry on their own work in their own way, because 

 biological research must always be acceptable. But, if the 

 Fishery Hoard should desire any special work to be done at 

 those stations, it has the staff, the knowledge of ways and means, 

 and the funds at its disposal, and the work will be done. 



England, unfortunately, is not prepared to the same extent. 

 It has no central body whose knowledge and experience of 

 fishery work in this and other countries could command the co- 

 operation of the different stations. It is doubtful also whether 

 the biologists in England have worked on the methods suggested 

 by the Congress. If so, they have not yet published any 

 results. They are so far removed, further, from the centre for 

 work, viz., the North Sea, that their work is formed on a differ- 

 ent plan ; they have not the same aims, and they do not look at 

 fishery problems as the biologists along the coasts of the North 

 Sea do. And it is a curious comment on this condition of Eng- 

 land, that on its East Coast— from which as much fishing is 

 carried on, and where the value of the fisheries is as great, as in 

 all those of the other countries round the North Sea combined 

 — it is curious that there is no station there which can adequately 

 take up the work proposed, and that a great part of this coast 

 is ascribed to Holland as within its area of investigation. All 

 this is said without intending any disrespect whatsoever to Mr. 

 Allen, but it comes to one's mind in reading over his proposals. 



The co-operation of the marine stations in England would 

 not remedy this. " A central bureau " for England alone would 

 require to be established, with experienced trained men at its head. 

 This would take much time and money, and when Great Britain 

 has been offered a "central bureau'" of more power and value 

 at a less cost, there can be little doubt for which the Govern- 

 ment will decide. 



Without intruding further upon your space by entering into 

 the advantages of the organisation proposed by the Congress, 

 and of co-operatiin with foreign countries, let me, in conclusion, 

 express my earnest desire to do justice to both sides. If Prof. 

 Herdman can prescribe a better programme of work, if Mr. 

 Allen can show a better organisation, then let us have them by 

 all means. The British Government will then have two definite 

 schemes to consider, and if it finds it cannot decide between the 

 two, then let us have two definite rival organisations, each 

 doing its best with the means at its disposal to add to the 

 knowledge and power of our country. Here we should be at 

 one, and rivalry will not be tinged with envy or bitterness, but 

 stimulate to greater exertions, and breed that respect and com- 

 munity of sentiment which springs from a common ideal and 

 hard work well done. H. M. Kyi.e. 



Naples, December 8. 



whatever to do with the November meteors. On November 15 

 the radiant of the Leonids sets at 2.30 p.m., so that the 

 observations of Mr. E. Shaw (quoted by Dr. Lockyer), Miss 

 Arden and some others are entirely put out of court, for we 

 cannot have a shower of Leonids with the radiant below the 

 horizon. 



The objects seen must have been purely imaginary, and they 

 may be easily produced by bending the neck and gazing intently 

 for a few minutes at a bright sky. I have observed many of 

 these spectral meteor showers on occasions when I have been 

 looking for Venus or some other object in bright daylight. 



It is astonishing that if one calls the attention of people to 

 imaginary phenomena of this kind and asks them to look, they 

 will, in ninety-nine cases out of one hundred, see the same thing 

 and encourage similarly mistaken ideas ! Yet if we observe an 

 unequivocal object, it is often very difficult to make others per- 

 ceive it and comprehend its character and the nature of the 

 observation. Fictitious objects are in point of fact often seen 

 more readily and apparently under more convincing aspects 

 than real ones, but this applies usually to inexperienced 

 observers. 



In addition to the two reports of the recent shower of Andro- 

 medids mentioned in the last number of Nature, there is a 

 third from Austria {Daily Chronicle, November 25). It appears 

 that the astronomers of the Vienna observatory, watching the 

 sky "from the beginning of evening up to moonrise, saw sixty- 

 seven shooting stars, mostly from Andromeda. A magnificent 

 fireball was also observed shining in the constellation. Twelve 

 photographs were taken." W. F. DENNING. 



Bristol, December 8. 



Birds Capturing Butterflies. 



Referring to the letters on this subject in your papers of 

 September 28 and November 16, 1 can certify to the fact of 

 robins chasing and catching large white butterflies on the wing 

 and swallowing them whole. In June we had ten robins coming 

 freely to the hand for food, and thus had frequent opportunities 

 of observing them daily. My gardener and his son have 

 witnessed the same habit of the robins. Howard Fox. 



Rosehill, Falmouth, December 7. 



Supposed Daylight Leonids. 

 The interesting details referred to by Dr. W. J. S. Lockyer 

 (Nature, December 7) of a shower of Leonids having been 

 witnessed by Miss Jeans and others at Swindon, and by Mr. E. 

 Shaw at Aveley, in Essex, on the afternoon of November 15 last 

 are corroborated by several other descriptions of a similar 

 nature which recently appeared in the newspapers. One of 

 these referring to a later date, was published m the Liverpool 

 Echo of November 21, and runs as follows ; — 



*' Sir,— Not having seen any account in the papers concern- 

 ing the arrival of the meteoric showers, I beg to state that I saw 

 them on Thursday afternoon, the i6th inst. I first noticed 

 them at 12. 15 ; they were shooting in all directions and kept on 

 until about 4 o'clock. Then on Friday, the 17th, I again saw 

 them at the same time. I called the attention of several people, 

 with the result that they could also see them. Owing to the 

 bright sky, one had to stare for a few seconds before perceiving 

 the stars, as they were very dazzling to the eyes. 

 " Yours, &c., 



" Liverpool, November 20." " Mima Arden. 



I need not quote any further descriptions, for there is not the 

 slightest doubt that the objects were illusory and had nothing 



NO. 1572, VOL. 61J 



VALVE MOTIONS OF ENGLNES. 



ENGINEERS want a diagram which for any position 

 of the main crank of a steam engine (the angle 6 

 which it makes with the inner dead point being given) 

 shows at once, with sufficient accuracy for practical 

 purposes, the position of the piston in its stroke, and the 

 distance of the valve from its mid position. This is a 

 mathematical problem. Men who are cunning in geo- 

 metrical constructions ought to help the engineers ; but 

 hitherto they have not done so. In the hope of enlisting 

 their services I venture to put before the readers of 

 Nature the only easy construction with which I am 

 acquainted. It has never before been published, except 

 to his students, by the inventor, Mr. J. Harrison, of the 

 Royal College ot Science. Until I became acquainted 

 with this method, I used a very laborious method of 

 working, which necessitated the drawing of sine curves of 

 different periods as described in my book on " Steam." 



It will save trouble in expressing my meaning if I 

 assume a uniform rotation of the crank. If we assume 

 that the motions of piston and valve are simple-harmonic, 

 a construction is very easy. When the valve is worked 

 directly by an eccentric its motion is very nearly S.H., 

 and in this case a construction, taking account of the 

 shortness of the connecting rod, is easy. 



But, as I have been trying to impress upon students for 

 many years, when a valve is worked by any ordinary 

 link motion or radial valve gear, the motion is not 

 simple-harmonic ; there is a small octave or kick of 

 twice the fundamental frequency, and if this is taken 

 into account, as well as the fundamental S.H. motion, it 

 will be found that higher harmonics are of very little 

 importance. Now in radial valve gears it is not at all 



