2/4 



NA TURE 



[July i8. 1895 



between the v ertical and the slope of the curve ; if more 

 than one, it will slope the other way, if it is neg^ati\e the 

 slope will be less than that of the curve. In order to apply 

 a general rule to all possible cases where both the index 

 connecting .V and I' and the index connecting the result 

 (y) with the variation of the constant may have any 

 \alues whatever, it is merely ncccssar\' to find a point a 

 upon the inclined straight line representing )• = ax , 

 at which j- is equal to u, or to that part of n which may 

 assume various values. At any distance above it rule a 

 horizontal line. Where the horizontal line cuts the inclined 

 line, write the figure o; where it cuts the vertical through 

 the point .(.write the figure +i. Then complete a scale 

 of equal p;irts on the horizontal line extending to + so and 

 — =0 . Lines drawn through the original point u and 

 any point f on this scale will be scale lines correspond- 

 ing to the case where the result depends upon the yth 

 power of the constant as well as upon the filh power 

 of x. 



The frequency cur\e placed upon the same chart has 

 two branches inclined at tan"' - ii and tan"'- i, joined by 

 a cur\e such that not only on the straight branches, but 

 at every- point, the algebraical difference of the tangent 

 of its inclination and that of the velocity curve for the 

 same value of .i' the wave-length is equal to unity. The 

 left-hand branch of the frequency curve supplies another 

 example of the rule given above for drawing a scale line ; 

 for, while its tangent is — i(, that of the scale line is - 3. 



It is evident that the curve may be con\eniently drawn 

 upon tracmg-paper, which may then be moved about, but 

 always keeping the inclinations unchanged until the 

 branches pass through the desired points upon the scale 

 lines. The numerical relations for the new constants 

 may then be read at once. 



I have thought it best to explain the method by the 

 use of a concrete e.xample. Of course it is not limited 

 to the case of ripples and wa\cs, but may be applied very 

 widely. 



By way of illustrating how to change from one system 

 of units to another, I have drawn a pair of double-ended 

 aji'iws in the middle of the chart, which show the mag- 

 n..ude and direction of the movement of each of the 

 curved lines with its straight dotted continuations, which 

 will be nccessar)' in order to read the results in inches 

 instead of in centimetres. The one relating to \elocities 

 is inclined at 45 , as both the velocity and wave-length 

 are equally changed in the ratio of 254 : i, or 1 : "3937. 

 On the other hand, the frequency being a mere number 

 is not affected, except in so far as the wave-length will 

 be expressed by a difierent number. Hence the direc- 

 tion of sliding is here horizontal and the same in amount 

 as either component of the other. The scale lines must 

 then be put in parallel to their former directions, and 

 running through points for which the vertical scale read- 

 ing has the numerical \alue of the constant according to 

 the system of units chosen. C. V. Uov.s. 



[No/e.- The numerical values represented by the ver- 

 tical and horizontal lines in each square in the diagram 

 are 1, r,, 2, rs, 3, 3-5, 4. 45, 5, 55, 6, 6-5, 7, 7-5, 8, 9, 10. 

 The nunil)cr of lines in the lluinan sheets is five times as 

 great, but they are drawn in three degrees of darkness to 

 distinguish them. — C. \'. H] 



JVOTES. 



A RKl'RK.>KSTA'llve meeting of friends and ailniirer.s of ihc 

 I.ilc Mr. Iluxicy ».xh held on Thursday afternoon, al Ihc rooms 

 of the Koyal .S'K:itly, under the chairmanship of Lord Kelvin, 

 I'.R.S., Ill CKriHidiT what .steps should 1m: taken ti> iniliatc a 

 national memorial. Ii was determined la call a general puhlic 

 meeting after the autumn rccevi, and, in Ihc meantime, to form 

 NO. 1342. VOL. 52] 



a general committee. Sir John Lubbock (15 Lombard-street) 

 has consented to act as treasurer, and I'rof. d. B. Howes (Royal 

 College of Science, South Kensington) as secretary to the pro- 

 visional committee. 



We notice, also, that it is proposed to establish a memorial to 

 commemorate the connection of Huxley with the Charing Cross 

 Hospital Medic.1l School. At a meeting held at the School on 

 Tuesday, the following resolution was passed : — " That the 

 memorial shall take the form of a Huxley scholarship and medal 

 to be awarded annually at the Charing Cross Hospital Medical 

 School, and that if funds permit an annual public lecture at the 

 Charing Cross Medical School dealing with recent advances in 

 science, and their bearing upon medicine shall be instituted." 



We understand that a large majority of those Kellows of the 

 Royal Society who have expressed an opinion on the matter, 

 being in favour of retaining the present quarto form of the 

 Philosophual Transactions, the President and Council have 

 decided to retain that form. As stated in a circular recently 

 addres-sed to Fellows, the President and Council, finding that 

 the majority of those expressing their opinion were in favour of a 

 royal octavo form for the Proccediiigs, have decided to adopt that 

 form. The change will probably be made at the beginning of 

 next year. 



Se\ER.^l new instances of generous gifts for the advance- 

 ment of scientific knowledge are reported in Science. Mr. Archi- 

 bald, President of the Trustees of Syracuse University, has 

 offered to be one of six subscribers for funds to build a hall of 

 science costing about ;f30,ooo. The University has also been 

 offered ;^2000 and ^'20,000 towards a new medical college. 

 Another American institution which has benefited by the 

 i epidemic of generosity which has lately prevailed in the United 

 States is the Johns Hopkins University, which has received from 

 Mrs. Williams a sum of money sufficient to establish a lecture- 

 ship in geology in mcmor)' of the late Prof, ('leorge 11. Williams. 

 •Sir Archibald Cleikie has been invited to lie first lecturer. 



The sum of ;f 50,000 required for the New York Botanic 

 Garden has been contributed by twenty-two donors. Sub- 

 scriptions of j^SOOO were given by each of the following : — 

 Mr. J. P. Morgan, Columbia College, Mr. Andrew Car- 

 negie, .Mr. C. ^■anderbilt, Mr. J. I>. Rockefeller, Mr. D. O. 

 Mills, Judge A. Brown. Mr. Wm. Ii. Dodge, Mr. J. A. 

 Scrjinser, and Mr. Wm. C. Schermerhorn each gave £2000, 

 and there were eight sub.scribers of /^looo each. The act 

 iif incorporation required that this amount be collected for an 

 endowment. The city must now raise ^100,000 by bonds for 

 building purposes, and provide 250 iicres of land in Itronx Park. 

 This part of (he agreement will proljably soon be carried out, so 

 New N'ork may look to possessing shortly a botanic garden of the 

 first order. Writing with reference to the prospect in Science of 

 July 5, Prof. Ci. L. (loodall, of Harvard I'nivcrsity, remarks: 

 " To Columbia College and the other educational institutions of 

 New York and vicinity, this new appliance for instruction will 

 mean indeed a great deal. To all the citizens who are to 

 lake .advant.ige of the opportunities for instruction which the 

 garden will afford, Bronx Park will be a constant delight. But 

 far beyond these limits, wide as they arc, the garden will exert 

 a profound and beneficial influence. Other cities will surely l)e 

 stimulated by this noble movement and enrich their park systems 

 with an educaliimal aid of the greatest value. Formerly lK)tanic 

 gardens, attached even in a remote manner to educational 

 institutions, were largely used for the cultivation of medicinal 

 plants, and for the reception of s|)eeies from distant lands. Of 

 course, this use, although its importance is now relatively less 

 than ever licfore, will still long continue to he a factor in the 

 direction of activities. But here and there new pha.scs of plant 



