, 



Jiuie 23, 1887] 



NATURE 



175 



tion for them. To invent names for the pound- foot-second units 

 may be helpful to beginners ; but it is a small matter compared 

 with a notaiion which completely specifies the mode of depend- 

 ence of each unit upon the pound, foot, and second ; and it is 

 still more so when compared with a general notation which will 

 serve for any system of units. 



The difference between names and notation is well seen in the 

 case of chemistry. The notation for a substance expresses the 

 manner in which the substance is made up of the elementary 

 substances ; while its name, however derived, serves merely as 

 .1 distinguishing mark : and just as the chemical notation for a 

 substance may be used as a name for the substance, so the nota- 

 tion for a physical unit may serve as a name for that unit. 



In my work on " Physical Arithmetic," published by Mac- 

 millan and Co. in 1885, and reviewed in Nature, vol. xxxi. 

 p. 551, I have devised a notation which is the natural and 

 legitimate extension of existing conventions both in language 

 and in the mathematics ; and I have made that notaiion the 

 basis of a method for solving problems in applied arithmetic. If 

 the Committee of the Association for the Improvement of Geo- 

 metrical Teaching are considering the subject, I ask them to 

 consider whether any notation more in harmony with existing 

 conventions can be devised than the notation of that work. 



As a specimen I append the general notation for the chief 

 geometrical, kinematical, and dynamical units. The word by 

 corresponds to X, and the word per to -r-, or / as now fre- 

 quently used by physicists. The same method of notation 

 applies to the thermal and electrical units. The notation for 

 any special system is obtained by substituting the special names 

 '»f the fundamental units L> M> T- The test of the value of 

 a notation is the amount of facility it offers in reasoning ; by 

 referring to " Physical Arithmetic," anyone may see how this 

 notation stands the test. 



Notation for General Units. 



Austin, Texas, May 28. 



Alexander Macfarlane. 



The New Degrees at Cambridge. 

 A FEW years ago it pleased the dominant body in the Univer- 

 sity of Cambridge to institute a Doctorate of Science and of 

 Letters. Candidates for these new degrees were required to be 

 of a certain academical standing, and to submit the proofs of 

 their qualifications to the respective Special Boards of Studies, 

 who, after certain formalities, were empowered to forward 

 their claims to the General Board of Studies for approval. 

 By many well-meaning persons this step was thought to be 

 a great encouragement to both letters and science. It was 

 at the same time understood that the qualification for the 

 Doctorate in Science was to be rather less than was required for 

 admission to the Royal Society — a standard which all will admit 

 is not too high. Whether any similar understanding was agreed 



upon as regards the Doctorate in Literature is uncertain. At 

 fir.-t there was no particular desire shown among the best men 

 of science and literature to aspire to the new distinction, and 

 it is rumoured that a considerable amount of persuasion and 

 friendly pressure had to be used to induce such men to submit to 

 the infliction. But in time a few leading lights underwent 

 the ordeal and were duly invested. The way being cleared, a 

 good many others have followed, and as the Boards have not 

 been too severe in judging »he claims of candidates, the outbreak 

 of " <^^carletina " has become rather general. However, no parti- 

 cular harm has ensued, and the coffers of the University have 

 reaped the benefit — for the fee is not small. 



But now there is another aspect to this business. The new 

 Doctorate is inferior in rank to that of the old Faculties. The 

 senior Doctor in Science or Letters must always yield precedence 

 to the youngest Doctor in Divinity, Law, or Physics. So far, those 

 who have sought the new degrees have known what their 

 position would be ; but of late the Council of Senate has taken 

 upon itself to determine that when an honorary degree should 

 be given to any distinguished man of science or letters he is not 

 to have the higher degree of LL.D., but to be content with 

 the lower rank. As a rule honorary degrees are almost in- 

 variably given to strangers — foreigners or colonists. They are 

 not aware of this fine though real distinction ; and thus 

 this very day the Senate House at Cambridge has witnessed 

 the time honoured and highly valued distinction of LL.D. 

 being conferred on a number of excellent gentlemen, beginning 

 with the Lord Mayor of London, while the new and inferior 

 rank of Sc.D. is bestowed on one of the most distinguished 

 biologists of the United States, whom the sister University is this 

 week to recognize as a D.C.L. 



It may be urged that proceedings like this are necessary to 

 reflect the proper amount of dignity on the new " honour," and 

 that in time it will be regarded as highly as the old one 

 has been. But I submit that this is not fair to the innocent 

 recipients, and, moreover, that the University should recognize 

 the fact that its highest honours are not to be bestowed upon 

 successful merchants, politicians, and persons of eminent social 

 standing, while the greatest men of letters and science have to 

 take up with the lower grade. OUTIS. 



June 20. 



" After-Glows" at Helensburgh. 



I BEG to inclose a letter from Mr. L. P. Muirheac', with refer- 

 ence to the "after-glows" recently seen at Helensburgh, which 

 you may think worthy of a place in Nature. 



Robert H. Scott. 

 Meteorological Office, 116 Victoria Street, London, S. W., 

 June 8. 



Rosemoiint, Helensburgh, jf une 4, 1887, 2xh. 



Dear Sir, — I do not notice any remarks in any of the 

 weather reports or in the pre>s concerning the after-glow=, and 

 as they may be local only, I drop you a line. All have lasted 

 about 45m. ; the first of any note, on the 17th, commencing well 

 down on the eastern, and finally fading away on the western, 

 horizon, all through of a deep rosy red reflected from the under 

 and western side of cirro-stratus. Again, on May 21, 23, 29, 

 30, 31, and June i. The last was peculiar, not only as being 

 the most lurid, the cloudscape being marvellously fantastic, but, 

 dying away at 2ih., it revived faintly at 2ih. l8m. to 2lh. 30m., 

 and again from 22h. to 22h. 20m., of a decided rose colour on 

 western side of roll-cumulus coming up from east-north-east. 

 Thursday, Friday, and to-night there is no glow ; overcast and 

 oppressive just now ; a little rain fell in forenoon. The glow 

 reminds mc, on a more intense scale, of that previous to 

 January 26, 1S84, and again on December 8 last year. 



From May 21, until to day, the weather has been genial and 

 fine. Faithfully yours, 



Lewis P. Muirhead. 



R, H. Scott, Esq., Meteorological Office, London. 



Zirconia. 



Somehow I overlooked for a few days the letter of Messrs. 

 Hopkin and Williams, which necessitatesabrief reply, since they 

 have confused (I am sure from mere haste) two samples, one of 

 which I never had, and a correspondence most of which took 

 place after what I had recorded. 



Briefly, these are the facts. I was informed by Mr. T. Bolas 

 that I could obtain "pure zirconia" of Messrs. Hopkin and 



