234 



SCIENCE. 



[Vol. XXI. No. 534 



on the very dates when the disturbed sections were in process of 

 being brought into view by rotation. Perhaps the most striking 

 illustration of the whole matter in a single instance is to be found 

 in the history of a great disturbance upon the sun in January, 

 1886. Upon the 12th of that month spots suddenly began to form 

 almost precisely at the meridian and about 10'^ south of the sun's 

 equator. Upon the four days following, these spots became 

 numerous, and some of them very large, covering an enormous 

 area, extending finally from the meridian almost half-way to the 

 western limb. It would seem that if magnetic effects ever pro- 

 ceed from the sun's meridian that this, above erery other, should 

 have been a case in point. But there was scarcely any disturbance 

 v?hatever and no auroras were reported from any source. On 

 Jan. 16 and 17 the magnets were entirely free from disturbance 

 when this great spot-gi'oup was undergoing many rapid changes 

 and was generally in the precise location to have a terrestrial 

 magnetic effect according to the idea which Professor Ricco 

 attempted to work out as above described. When, however, this 

 area was at the eastern limb, from Jan. 7 to 11, although it had 

 not yet developed spots and was the seat of groups of brilliant 

 faculse only, there was an entirely different state of affairs, a 

 great magnetic storm being in progress and auroras being reported 

 generally from localities in high latitudes. Thus it appears that 

 it is not faculce in general that produce such marked effects, but 

 faculse in the location of areas frequented more or less persistently 

 by spots, etc. M. A. Veedee. 



Lyons, N.T., April 14. 



Where is the Litre ? 



I HAVE read Professor Mendenhall's contribution to Science of 

 April 21 with surprise. I did not think it possible for so eminent 

 a man to so entirely miss the point of any article he might con- 

 descend to read and criticise. Nor did I think it possible for so 

 keen-witted a controversialist to so entirely forget his own argu- 

 ment as to admit and corroborate the very statements he set out 

 to refute. Yet any reader of Science who may take the trouble to 

 read the two articles written respectively by Professor MendenT 

 hall and myself under the heading "Where is the Litre?" will 

 see that both of the unlikely events in question have happened. 



I invite my distinguished critic to re-peruse the paper he attacks, 

 and to thus ascertain whether it contains any statements or con- 

 tentions displaying "ignorance of the recognized principles of 

 metrology," or whether it sets forth " certain conclusions which 

 will generally be harmless on account of the very magnitude of 

 their errors " If he can find any statements, contensions, or con- 

 clusions that appear to him to justify such descriptions, let him 

 quote them in their ipsissima verba, and let him show in what 

 manner they betray ignorance or error. I will then, in my turn, 

 show the Professor to be mistaken. 



This is no over-bold challenge. It is almost self-evident that 

 Professor Mendenhall was unable to find any display of ignorance 

 or any erroneous conclusion in my article ; as, in that case, he 

 would naturally have quoted the offending passages in justifica- 

 tion of his severe remarks. But his only approach to quotation 

 is worded as follows: "The sermonizing finish to the article, 

 beginning with the sentence, ' In spite of the much lauded sim- 

 plicity of metric measures,' etc., may, however, mislead a few 

 readers whose ideas have been befogged by the perusal of the 

 previous three pages." Such a reference is too loose, too indefi- 

 nite, and too general to indicate what particular statements or 

 conclusions are objected to; and the Professor's scornful allusion 

 to easily-befogged readers of Science is, perhaps, too donnish. 



And now, while leaving my critic to the digestion of my chal- 

 lenge, I may, without impropriety, quote some opinions that have 

 reached me from other authorities. 



1. The Engineering Newsol March 30, in an editorial reference 

 to my paper, says: " Different enactments by legislative bodies, 

 errors in measurement and in calculation, difference in weights 

 between bodies weighed in air and weighed in vacuo, Snd differ- 

 ence in weights between water containing air and water freed 

 from it have conspired to produce these variations. It is true 

 these variations are all so small as not to affect the practical ac- 



curacy of any ordinary measurements; but for the exact work of 

 physicists and chemists, and for some of the finer measurements 

 of engineers, these variations are sufficient to affect the results. 

 The moral which Mr. Emmens points is that the author of any 

 paper or treatise claiming scientific accuracy, and dealing in 

 quantities whose exact values may be in doubt, should preface his 

 work with a statement of the constants adopted throughout the 

 work. In a personal letter to us Mr. Emmens makes the further 

 suggestion that the international congress of scientists and engi- 

 neers at Chicago next summer will afford an excellent opportu- 

 nity for defining anew the metric standards whose values have 

 become most variable, thus restoring to the system the advan- 

 tages of simplicity and freedom from ambiguity which it was 

 originally intended to possess. It certainly gives good ground 

 for criticism that in every school in the land pupils are taught 

 that the litre is equal to the cubic decimetre, whereas, in reality, 

 the litre is about 0.1 cubic inches larger than a cubic decimetre, 

 the exact variation depending on what value is chosen for each." 



2. Professor Be Volson Wood, of the Stevens Institute, writes: 

 "Your article in Science, ' Where is the Litre? ' is such a model 

 of courteous discussion that I thank you for it. The closing re- 

 marks contain sentiments I often advocate, but you have done it 

 so much more completely and in all respects so much better 

 than I could, that I appreciate it." « 



3. Mr, R. A. Hadfield,of the Hecla Steel Works, Sheffield, Eng- 

 land, whose scientific reputation is world-wide, writes: " It ap- 

 pears to me you have touched tbe weak point of the Metric sys- 

 tem, and it was only the other evening, at a lecture on this sub- 

 ject, that I was aware for the first time there was a difference 

 between the litre and the cubic decimetre. No doubt many 

 others are in the same way, and it would therefore be specially 

 desirable to have some common understanding on this matter." 



4. Mr. Latimer Clark, F.R S., writes : "I will see the Board 

 of Trade with your letters. They are as anxious as you or I can 

 be to help in such a cause, and would do anything to promote it. 

 The Chicago conference would afford a capital opportunity for 

 raising the question, and I will do anything required if you will 

 point out what you recommend. The difference between the 

 litre and cubic decimetre is simply one of popular belief and 

 teaching, and it arises from the French Bureau having decided 

 to adopt the bulk of the kilogramme of water as the bulk of the 

 litre. I may perhaps add that the Warden of the Standards here 

 has written me that he acknowledges my dictionary as correctly 

 setting forth the values they have adopted and are employing, 

 and he adds that he recommends the book to all enquirers on the 

 subject." 



I refrain from adducing further evidence lest I should put Pro- 

 fessor Mendenhall in the position of the dissentient juryman who 

 complained that "he had never before, in the whole of his life, 

 met with eleven such obstinate fellows." 



Stephen H. Emmens. 



Toungwooa, Pa., April, 25. 



Sham Biology in America, 



Mr, Conway MacMUjLan has shown more enthusiasm than 

 discretion io his recent article. He is writing in a good cause, 

 namely, the elevation of botany to an equal rank with zoology in 

 biological teaching in universities. Biology, however, is not the 

 science of animals and of plants, as Mr. MacMillan maintains, it 

 is rather the science of life; and I am not aware that biology is 

 taught in any large institution in this country without taking ad- 

 vantage of the fact that certain laws and principles of life are, 

 for purposes of practical study, far better shown in plants than 

 in animals. Plant biology is therefore extensively taught upon 

 the lines laid down by Huxley and Martin, and on such lines we 

 simply select the organism which best demonstrates a certain 

 principle. If the botanists of this country allow the zoologists to 

 take^e lead as biologists, that is, in setting forth tbe fundamen- 

 tal pmiciples of life from their observations upon animals, it will 

 naturally follow that zoology will occupy the leading position in 

 the universities. Mr. MacMillan's argument should therefore be 

 directed to the botanists and not to the zoo'ogists, who are in no 



