272 



NATURE 



[July 23, 1908 



are discussing this particular subject. Tliey are dealing 

 more especiallv with symbols for electrical and magnetic 

 quantities, but the system might with advantage be ex- 

 tended to embrace all important quantities in physical 

 science, especially as the subject is receiving the attention 

 of most technical societies with a view to some action being 

 taken in the matter. 



There are, however, two great difficulties which arise 

 when we try to fix upon a standard notation. 



The first is the difficulty of persuading a number of 

 writers and readers who have become accustomed to a 

 certain symbol for a certain quantity to change it in 

 favour of an equally large number of writers and readers 

 who have become accustomed to another symbol. I'or 

 instance, in France and Germany the letter " 1 " com- 

 monly represents the strength of an electric current, while 

 in England and America " C " is more commonly used. 



In the second place, there are not enough letters in the 

 two or three alphabets at our disposal to give a distinct 

 symbol to each quantity, without resorting to the com- 

 bination of more than one letter to form a single symbol. 

 There is a great objection to this combination of letters, 

 because the use of subscript letters and numbers is re- 

 quired for distinguishing between particular quantities of 

 the same general kind. If, for instance, C represents 

 current, C„ might conveniently represent armature current, 

 and C, the current in circuit No. i. It would therefore 

 not be good to take C„ to represent capacity, or any 

 quantity other than an electric current. 



There is, moreover, an objection to using letters at all 

 to represent quantities in a universal notation, because, 

 unless initial letters are used, there is no connection in 

 the mind between the letter and the quantity, and the 

 symbol is difficult to remember. We cannot always use 

 initials, because the initial letters differ in different lan- 

 guages. For instance, in England " R " commonly stands 

 for resistance, while in Germanv it is more convenient 

 to use " W " for widerstand. Moreover, the same initial 

 occurs for a great number of different quantites. For 

 instance, " R " might stand for resistance, reluctance, re- 

 actance, radius, &c. 



One way of avoiding the above difficulties would be to 

 create a number of new symbols which could be printed 

 by means of type like ordinary letters, and which would 

 represent each physical quantity in a distinctive manner. 



The question, however, arises as to whether a number 

 of entirely new symbols would be acceptable to writers, 

 readers, and printers alike, and the sub-committee on 

 symbols appointed by the British section of the Com- 

 mission has requested the writer to place his views publich 

 before the profession, with the view of obtaining sugges- 

 tions and criticisms as to the feasibility of such a scheme 

 from as wide a circle as possible. ' ■ 



In choosing a symbol, we would try to make a very 

 simple picture of something that reminds us of the quan- 

 tity in question. For instance, | might represent temper- 

 ature. If wo were told that this simple outline of a 

 thermometer represents temperature, we would have no diffi- 

 culty in remembering it. Similarly, / might represent 

 force, and the various "forces" might be derived from 

 it ; for instance, 1/ electromotive force (conventional repre- 

 sentation of lighting), and f) magnetomotive force. 



It is not my purpose here to say what would .actually be 

 the best form of symbol lor each quantity, but it is not 

 a ditTicuIt matter to devise very simple characters which 

 can be written quickly, easily, and with sufhcient accuracy, 

 and can at the same time assist the memory to connect 

 them with the quantity for wljich they stand. 



What would the printers say to the new type? The 

 author has taken up this matter with a very large pub- 

 lishing firm, and is assured by their chief expert that 200 

 or 300 new types would be a small matter to a modern 

 printer, who is already accustomed to deal with many 

 hundreds of different founts, each of which contains from 50 

 to 120 different symbols. He estimates that a printer in 

 a large way of business has at his command as many 

 as 60,000 distinct types, differing from each other either 

 in letter, size, body, or face. The addition of 200 or 300 

 more would be a drop in the ocean. The size of the 

 new type could be standardised for most purposes, and it 



N'O. 202 T, VOL. 78] 



would only be in some special case that another size would 

 be called for. 



The setting up of the formul;e with the standard size 

 of type would be simpler than with the present system, in 

 which subscript letters are often unnecessarily introduced. 

 One symbol under the present system sometimes consists of 

 four or five letters. 



If it be admitted that the introduction of new symuols 

 is advisable, the question arises, what shall the new 

 symbols represent exactly? Shall the sign j (temp.) re- 

 present temperature in any units, or shall it represent 

 the number of degrees of temperature, measured by some 

 scale agreed upon, and embodied in the definition of the 

 symbol? If the system of units employed be not prescribed, 

 fewer symbols would be required, and the general writer 

 who now says vaguely, " Let T equal the temperature.'* 

 would find the symbol sufficient for his purpose. But from 

 the reader's point of view there is much to say in favour 

 of a symbol which will embody in its definition a standard 

 system of units. ;\ny formula expressed in such symbols 

 would be completely self-contained, and would be an exact 

 statement of a physical fact. Until the units employed 

 in any formula are known, the formula expresses only 

 half its meaning. Perhaps some slight addition to the 

 symbol, or even to the whole formula, might be used to 

 indicate that the standard system of units is employed. 

 Without that addition, the symbol would have a general 

 meaning. For instance, \ might equal temperature, while 

 i might indicate the degrees centigrade above the absolute 

 zero. The name of the type might bo the name of the 

 physical units which it represents ; for instance, for If 

 wo might read "volts." 



If writers, printers, and readers who have any definite 

 views as to the best method of devising a system of 

 symbols would communicate with the author, they might 

 assist in solving the many difliculties which arise in con- 

 nection with this matter. Miles Walker. 



The Cottage, Leicester Road, 

 Halo, Altrincham. 



Linnacus's Authorities. 



I AM happily able to throw a little light upon the question 

 raised by Prof. Karl Pearson in N.\TURE of July 16 (p. 247). 

 The citation he quotes is identical with that in the tenth 

 edition of the " Systema Natura; " (1756), p. 24. 



" Boat. jav. 84. t. 84." will be found in Piso, " De In- 

 dite utriusque re naturali et medica," .-\mst. 165S. fol. The 

 bastard title following the engraved title-page has towards 

 the bottom this line : — " lacobi Bontii, Batavire in majore 

 Java nova; medici ordinarii, ..." hence, no doubt, the 

 form employed by Linn;eus. This forms the third separately 

 paged part of the volume, and on p. 84 is a Woodcut 

 of the " Ourang Outang sive Homo silvestris," &c. 



" Keep. itin. c. 86 " is doubtless " Kioping (Nils Mat- 

 son) En reesa geriom .Asia, . . . . &c. \Visingsborgh, 

 1667. 4to."; I am quoting from Dryander's Catalogue 

 of Banks's Library, vol. i., p. 86. 



" Dalin. orat. p. 5." is referred to in Amcen. .Acad., 

 vol. vi., p. 74 as " Dalin in oratione Acad. R. Holm, de 

 hac : " &c. I have not verified the actual speech, but it 

 should not be difficult to run it down in the early volumes 

 of the Handlingar. B. D.wdon Jackson. 



Linnean Society, Burlington House, W. 



Elliptical Halos. 



In Pernter's " Meteorological Optics " the explanation 

 of haloes, based on a consideration of refraction and re- 

 flection in ice-crystals, is given at some length. In par- 

 ticular the elliptical halo described by Mr. Cave in Nature 

 of July 16 (p. 247) is shown to be a form depending on 

 the sun's altitude. If the sun is less than 25° above the 

 horizon, the phenomenon appears as two arcs touching 

 the 22° halo at its highest and lowest points. F'cr altitudes 

 greater than 70°, it is indistinguishable from the 22° circular 

 halo. 



It would be interesting to know if Mr. Cave observed 

 the transition from the elliptical to the circular form. 



E. Gold. 



3 Devana Terrace, Cambridge, July 16. 



