8o 



NA TURE 



[Nov. 27, 1884 



preached an annual sermon from the same text. It is certain 

 that the sympathies of the public would be alienated ; and if 

 those hearers who are taken to task were to follow consistently 

 the lesson inculcated, they would occupy themselves entirely with 

 objects of pecuniary gain instead of providing the discoveries 

 which our manufacturers are so much in need of, or advancing 

 learning by their contributions to the Philosophical Transactions. 



W. N. Hartley 



Our Future Watches and Clocks 



In reference to the note on this subject in Nature (p. 36), it 

 appears to me that to any radical change in dial-division there 

 exist many objections, of more or less weight, over and above 

 those already enumerated. In regard to — 



(A) Striking the hours. — (1) It is said that "public clocks 

 . . . could not go on to twenty-four." The same would apply 

 to private clocks as well, as the higher numbers would be struck 

 during the — to children and many others, sick or well — early 

 hours of sleep, when greater disturbance from house clocks than 

 at present occurs would be quite unendurable. The counter- 

 advocacy of silent house clocks would scarcely meet the case. 



(2) The alternative suggestion of " one stroke only at each 

 hour" would do away with one important function of public 

 clocks, that of marking to watchless people the exact hour. 

 Persons abed, lonely watchers, and field-labourers, commonly 

 depend upon the church clock for information which could only 

 be acquired otherwise with much discomfort. 



{B) The 2.^-division plan. — (3) That no diminution in "the 

 angular motion of the hand " during any given time should be 

 brought about seems most vital. The time of day is often ob- 

 tained from far-distant clocks, and is even at present not easy to 

 decipher readily, especially under circumstances of inadequate 

 ight or visual power. 



(4) Similarly, in the case of any slight looseness in the hands 

 — a commonly-neglected chronometric infirmity — it would be 

 harder than ever to decide at a glance what hour is indicated. 



(5) It will be observed that the adoption of this plan would 

 aim 1st necessitate half- minute arcs. 



C) The double 12-division plan. — (6) Inasmuch as the pre- 

 sence of two concentric circles of figures of undiminished size 

 would shorten the clear effective length of the hands, the arc 

 subtended by the hourly angle w ould be diminished by much 

 the same extent as in the previous plan (B 3), and a similar 

 objection would apply. 



(7) The presence, in any form, of twenty-four symbols, in 

 addition to the maker's name and the like, in the dial area, 

 especially in ladies' time-pieces, would be eminently confusing, 

 and restrictive of instantaneous decision as to what the time 

 may be. 



8. Even if, to obviate all this — a point suggested by the 

 statement that "persons probably pay small attention to the 

 figures " — a single circle of twelve conventional symbols, iden- 

 tical or not, such as a radial arrowhead, were adopted to 

 indicate the a.m. and the p.m. hours in their turn, one 

 would have to undergo the added mental labour of deciding the 

 actual number of the hour. 



(9) In any case the introduction of a "o" hour, unless we are 

 to adopt railway phraseology, would be most awkward, and in 

 the "double 12-division plan" the transition at noon and 

 midnight from one circle to the other would not be a simple 

 sequence. 



Finally, the question arises whether the now common time- 

 pieces, in which the hands are either replaced or supplemented 

 by a series of peep-holes, wherein the minute, hour, and even 

 week-day for the time being, are consecutively displayed, would 

 not aid the introduction of the twenty-four hour system into 

 rough general use. The main disadvantage of abolishing the 

 hands is that one would lose an actual picture suggestive of the 

 time which will elapse between the present and any point in the 

 near future. For all purposes for which closer chronometric 

 accuracy is required, the above stumbling-blocks to change in 

 dial-division, arising out of the pressing value in ordinary life of 

 the ability to tell the time swiftly, and without undue mental 

 effort, would be swept away. ERNEST G. HARMER 



88, Buckingham Road, N., November 19 



As regards the practical question how clocks are to be made 

 10 strike if the dial is to show twenty-four hours, I have a sug- 

 gestion to make. 



But firstly, the convenience of beginning the day at midnight 

 is evident, as the early morning hours are those which it is most 

 useful to have indicated to the ear, and our clocks may continue 

 to strike from I a.m. to 6 as now. 



The inconvenience of having to count any number of strokes 

 above six is so great, and doing it so tedious, that most persons 

 break down in attempting it with a slow-striking clock ; and I 

 think that there is a good deal to be said for the system, which 

 obtains in some places where the hours are still reckoned as 

 twenty-four, of beginning afresh at the end of every six hours, 

 and denoting 7 and 13 as I, &c. This plan would make very 

 little or no change. 



But what I wished to suggest is : That clock-makers should 

 make the clocks to beat the strokes in pairs ; e.g. two strokes 

 and a rest + two strokes and a rest + one stroke, would be 5. 

 This would be counted as easily as 3. Moreover, there would 

 be no occasion under ordinary circumstances to count the strokes 

 at all ; whether the hour was odd or even would be all it was 

 necessary to learn for one to know which hour it was of the 

 twenty four. One may, for instance, in the morning doubt 

 whether it is 10 or II, or whether it is II or 12, but one rarely 

 doubts whether it is 10 or 12. And on the principle I recom- 

 mend, the last stroke of the clock being single or double would 

 decide the matter. One would not even have to attend to it. 

 I contend that under the present system it is impossible for a 

 person with only ordinary patience to discover whether a clock 

 strikes 1 1 or 12. 



If you think anything of this suggestion, which I have always 

 thought myself to be a fair solution of a difficulty, I shall be 

 glad if you would insert it in your paper. R. B. 



Light ning-Conductors 



In the Edinburgh Review of last July many of your readers 

 will probably have noticed an article on " Lightning-Conduc- 

 tors," written somewhat strongly from the point of view of an 

 advocate of the apparatus thus popularly designated. Perhaps 

 a few words of comment on this paper from a rather different 

 aspect may not be without interest to those who are able and 

 willing to treat the subject with unprejudiced minds. 



In the reviewer's narrative of the history of lightning-rods he 

 omits all mention of Franklin's initial letter of September I, 

 1747 — that letter in which the great discovery of the power of 

 points is given to the world. But it is abundantly evident from his 

 subsequent letters of 1749 and 1 750, in which he definitely fore- 

 casts the invention of rods, that it was to his knowledge of this 

 power — and of this power alone — that he owed the idea of these 

 instruments. In other words, his original conception was purely 

 that of an apparatus for preventing the occurrence of a lightning- 

 stroke at the place where the rod was erected. Now, if I am 

 not mistaken, the reviewer from first to last never alludes to this 

 all-important function. It is true that Franklin himself after- 

 wards fell in with the curious supposition that these rods acted 

 as "conductors" of a stroke. But (so far as can be judged 

 from his letters) this was not till September 1753, at which time 

 most of the European scientific men, themselves either ignorant 

 or sceptical of the preventive power of points, had fully adopted 

 the invention and had invested it with the theory, that has ever 

 since been accepted, of its being a means of "conducting" past 

 the building a stream of fiery matter (denoted as "electric 

 fluid") descending from the clouds to the ground. Now it is 

 evident that nothing can conduct the agency known by us as 

 " lightning " without first being struck by it ; and it is also mani- 

 fest that, in order to be so struck, an object must present some 

 "attraction" to the stroke. This attraction — this necessary 

 first step to conduction — allowing for the nonce that an explo- 

 sion such as constitutes a lightning-stroke can be conducted — is 

 a matter that usually (and not unnaturally) is treated by those 

 who believe in lightning-rods with some little reticence. I 

 therefore think it is but fair to give credit to the reviewer for 

 the open and honourable manner in which he enunciates his 

 views of the true function of lightning-rods. He says (p. 40) : — 

 " Conductors provided by engineering art are intendtd to be 

 struck, but struck in such a manner as to govern the lightning 

 and to render the heaviest strokes harmless." There is no beat- 

 ing about the bush. He admits that his conductors are pur- 

 posely fixed on a house in order to attract a stroke to that house 

 with the view of afterwards rendering the effects of the explosion 

 nugatory. Now the very essence of the opposition that has 

 been made to the use of these conductors lies in this very fact of 



