500 



NA TURE 



{Feb. 15, 1872 



money into so many parts, and not finding how many 

 times the number 365 is contained in so much money, 

 which is meaningless. (2.) Multiplication is said to be 

 only a shorter method of " getting at " a particular kind 

 of summation ; but when wc come to fractions we are 

 told parenthetically that to multiply 7 pence by J is to 

 take three-quarters of it, without any discussion of the 

 extension of the very meaning of the word multiplication 

 that must be made before this interpretation is intelligible. 

 In the same way we are told that one way of writing 

 2S9 ^ 17 is --^f before the important truth has been im- 

 pressed on the' pupil that J of 3 = J of i, so that a symbol 

 is used in two distinct senses before the identity of those 

 senses has been shown. Throughout the book all dilti- 

 cuhies are slurred over with half reasons, which are to be 

 accepted by the pupil as whole ones. There is no attempt 

 to lead the pupil to discover the rules for himself, or to 

 trace the way in which they were originally arrived at ; 

 while at every turn we meet with such expressions as 

 " evidently," " it is clear," " it is easy to see," " there is no 

 mystery about decimals," as substitutes for the considera- 

 tions which should really connect the new rules with the 

 previous knowledge of the pupil. We might pick out 

 specimens of this want of thoroughness from almost every 

 page, but wc must now turn to the art of arithmetic. The 

 author says " care has been taken not to introduce any- 

 thing in the way of mathematical invention or discovery," 

 but surely care should also have been taken that the book 

 should not be behind those already published in the brevity 

 and completeness of the methods given. The rule for 

 contracted multiplication is given, but its application to 

 complicated calculations, such as practice, interest, stocks, 

 &c., is left untouched. Contracted division is mentioned, 

 but is not apphed to the only case where it is indispens- 

 able, division by an interminable decimal. Decimalisa- 

 tion of money is taught, but by the old clumsy method ; 

 while a mode of appro.ximate decimalisation is given, which 

 is of no use if the result required be greater than the given 

 amount. The latter portion of the book is devoted to 

 mensuration, in which considerations that belong to the 

 higher mathematics are described as evident, while all 

 mention of the mensuration of rectangles and the differ- 

 ence between linear, square, and cubic feet is omitted. 

 The book is below the level of the more advanced thought 

 of the age, and unworthy to take rank in the series which 

 contains "Miller's Inorganic Chemistry," and "Maxwell's 

 Theory of Heat." H. A. N. 



LETTERS TO THE EDITOR 



[ The Editor does not hold himself responsible for opinions expressed 

 by his correspondents. No notice is taken of anonymous 

 commujiications. ] 



The Total Ecli'iJSe as seen at Ootacamund 



As a photographer and an ardent lover of science, I was of 

 course anxious to catch an image or two of the eclipse, as a 

 memovial of the grand scene of the morning of the 12th inst. 

 Unfortunately for me, I read a short time ago an article liy Mr. 

 Brothers, of Manchester, on photographing eclipses, in which 

 he says that it is useless to attempt a photograph of an eclipse 

 without an equatorial stand to fix the camera to. Inquiries soon 

 convinced me that in a primitive place like this it was impossible 

 to get such a stand, and, in consequence, I gave up all idea of 

 making an attempt at taking a photograph of the ecUpse._ The 

 eclipse, however, no sooner commenced, than I laid aside my 

 telescope and brought my camera into use to watch the pro- 

 gress of the eclipse, with the aid of a strong magnifying glass on 

 the focusing screen of the camera. Here I saw that the pro- 

 gressive movement was scarcely perceptible ; and that, with a 

 short exposure of three seconds, I might get an image : though 

 not perfectly sharp, yet it might show all details necessary for 

 forming an interesting memorial of the eclipse. 



I prepared one plate some time before totality, washed it, so 



that it would keep good for an hour or so, and some time after 

 totality had commenced I exposed it for three seconds, and de- 

 veloped it some time after totality. As far as I know I exposed 

 the plate 75 seconds after the commencement of totality, and the 

 resuU was the plate I had the pleasure to hand to you, and the 

 prints you saw in my place were printed from it. I may add 

 tliat the plate wa; taken with a No. 6 D. Dallmeyer's lens, with 

 the full opening and without a stop. 



I will digress for a moment and express my surprise that I heir 

 that the photographers of the Expedition parties obtained only 

 five or six plates during totality, and that they gave exposures of 

 about 15 seconds. If I had exposed my plate 15 seconds instead 

 of three, I should have had nothing remaining but "a foggy ghost." 

 There must have been a great want of proper balance in their 

 chemicals, .'\gain, they seem to have been provided with a 

 number of slides, or camera-backs, to hold a certain number of 

 prepared plates. Now, had I known that I could obtain toler- 

 able results witltout an equatorial stand, I would have presented 

 you with a plate of at least eighteen different photos of totality. 

 As my idea may be useful on a future occasion, I will shortly 

 mention it. Photographers are in the habit of taking 2, 4, 6, or 

 even eight cartes de visite photos on one single plate, and often 

 also with one lens only, by an arrangement which we call repeat- 

 ing backs. A slight modification of the repeating back would 

 have enabled me, or any one else, to take in quick succession, 

 without loss of a second, at least iS or 20 photos of the eclipse 

 on one single plate. Different exposures might have been given 

 to some or to all, and a treble number of photos to what has 

 been obtained might have been secured without additional ex- 

 pense, and with les; troul:)Ie. Any apparatus-maker would 

 furnish such a slide for about 40,(., and as the operator would 

 have only to pay attention to one slide and one plate, he would 

 work with more certainty and comfort. If any one will say that 

 one good photo of the eclipse was all that was needed, I must 

 say that I differ from him. I observed most distinctly that the 

 shape of the corona was undergoing a regular dissolving view 

 process, and had not for two seconds exactly the same shape. 

 Of this more hereafter. 



The eventful day commenced here in the centre of Ooty, with 

 the sky overcast both in the east and west with dark grey clouds. 

 The camp of the Expedition on Dadabetta appeared enveloped 

 in fog, so that the early prospects of the members stationed 

 there must have been rather gloomy. In the town where I was 

 the eclipse was visible from the very first commencement to the 

 last moment ; only once, for a few seconds, during the earliest 

 stage, a small cloud obscured the sun. The grey, gloomy clouds 

 receded (as if inspired with fear) .as the eclipse advanced, in the 

 direction of aU four points of the compass, and the atmosphere be- 

 tween the earth and tite sun and moon appeared of that absolute 

 pure and blue Ime, which can seldom be seen anywhere else except 

 in high mountains. The scene as seen from the centre of Ooty 

 w as a grand sight. Every eye was turned to tlte east, the curious 

 play of colours around the hidden sun, the general gloom or 

 want of light, the ghostly shadows thrown by trees and other 

 objects, the clear appearance of the stars in the west, combined 

 with the solemn stillness (which we enjoyed at Ooty) not a breatli 

 nor a leaf moving, combined with all the other novelties of a 

 total eclipse, formed a scene which is easier im.igined than 

 described. Chickens and fowls were of opinion that the day 

 was ended, and retreated to their roosts, and many old people 

 (natives of course) hid themselves in their huts, filled with 

 anxious expectations of the things which were to come. The 

 whole scene was still more enhanced by a large assembly of 

 natives which had assembled near my place. Their exclamations 

 of fear, of terror, and awe, were very amusing if not distracting. 

 Now their fear showed itself by short and earnest incantations 

 or prayers to a certain good deity to deliver the sun from the 

 cruel fate of being swallowed by the large serpent, which, in 

 their opinion, constantly pursues the sun, and overtakes it 

 during an eclipse, and when only the interference of a good deity 

 can save the sun from the fearful fate of having to undergo digestion 

 in the belly of the terrible serpent. Some began to smite their 

 breasts, and pluck their hair, accompanying these acts with ex- 

 clamations which betrayed no small a.iiountof mental agony about 

 the probable fate of Father Sol ; others A\atched in trembling 

 silence, awaiting the end with fear, but coupled with hopes that 

 the prophecies of the holy Brahmin might yet be fulfilled. 

 Higher and higher rose the excitement, until the entire sun was 

 engulphed in the terrible serpent's mouth. But it happened, as 

 the Brahmins had foretold, a powerful good deity cut off with 

 one blow the big serpent's head, and the sun, instead of going 



