Jan. 22, 1874] 



NATURE 



223 



then passes up the valley of the Indus, but without watering that 

 large extent of desert lying between Scind and the Punjab, so it 

 is not till within a short distance of the liills that the body of air 

 begins to part with its moisture. 



I say this is all a very interesting subject to study, but it is not 

 my intention at present to go into it, but simply to state that this 

 season Bengal has not had its average rainfall, while in the 

 I'unjab the rains were later than usual in setting in, yet the 

 general fall has been on the whole seasonable, for though the 

 cotton crop is a failure compared with other years, yet the cereals 

 have been plentiful, and hence grain is|.cheap. 



In Fig. I I have tried to show the price of grain along the line 

 of the railway from Umritsur to Bhaugulpore, a distance of 1,047 

 miles. The full black line shows the actual prices at which grain 

 is now selling in all the several districts through which the railway 

 passes, it being least at Umritsur, which is in the centre of the 

 Punjab, and greatest at Dinapore, in the Patna district of Bengal. 

 At the right-hand side is a scale of rupees showing the cost per 

 maund, which can be easily reduced to English values by consi- 

 dering a manud equal to \ cwt. and a rupee equal to 2s. This 

 will approximately give the present English value of wheat 

 during November last as published in the several gazettes. The 

 lower dotted line shows how the price of this grain goes on in- 

 creasing by the distance transported. The usual railway rate 

 was i pice per maund per mile, which by a late order of Govern- 

 ment has been reduced to half this rate, or approximately 3^. 6./. 

 for 100 tons a mile. 



If to this be added 15 per cent, protit to meet losses and 

 deterioration, the thick dotted line indicates what grain could 

 probably be sold at by Government without any loss, if it 

 became a large dealer ; and, as before said, the upper full line 

 shows the actual prices with the large margin there is for profits. 

 Fig. 2, however, shows this much clearer, and proves that 

 the demand must be greater than the supply ; or, in other 

 words, that as much as over some 2,000 tons daily of grain, 

 which was grown more than 700 miles away from the point 

 where the famine is most severe, along the line of railway, is sent 

 down from the Punjab, and the highly irrigated lands of the 

 North- West Provinces, enough to sustain in life as many as there 

 are inhabitants in London, or some four million souls ; for i:^lbs. 

 for each man, woman, and child, is considered enough to sustain 

 the life of a native of India. 



But what is this to the millions of Bengal that are now threat- 

 ened wth famine? It is hardly one-seventh, I am led to 

 understand. So with all our canals and railways, and the great 

 good they are doing in the present state of things, yet there is a 

 larger demand than can be supplied, or the profits could never 

 mount up to 70 percent., as at Dinapore. 



Though the subject of this letter may not be considered 

 exactly a fit one for the pages of Nature, yet I feel sure that 

 those who study Nature in her works and effects, will be in- 

 terested in the facts now given. 



T. Login 



Sup. Engineer, Punjab 

 Umballa, Dec. 12, 1S73 



Dr. Tyndall and Sensitive Flames 



In the last number of N.\ture a report is given of the first 

 of Dr. Tyndall's Christmas "Lectures to Juveniles," on the 

 Motion and Sensation of Sound. In that lecture Dr. Tyndall 

 shows how the reflection of sound can be made manifest to an 

 audience by means of a sensitive flame ; and, according to the 

 closing words of your report, Dr. Tyndall states, — " Never before 

 have these phenomena been made visible. Hitherto these effects 

 have been investigated by the sense of hearing ; I have now been 

 able to prove them by appealing to your eyes." 



In the Illustrati-d Liindon A'crcj a short notice is also given of 

 the same lecture, and there Dr. Tyndall is reported to have 

 said, that no philosopher had ever before witnessed the reflection 

 of sound until that afternoon. I presume, therefore, that the 

 report you have given accurately repres'jnts Dr. Tyndall's words. 

 And this being so, will you permit me simply to place the fol- 

 lowing facts before your readers. In January 1870 I published 

 an arti'-'lc in the Quar/cr/y yoHinal of ScieiKc on the 

 " Analogy of Light ant Sound." In that article I stated how 

 a sensitive flame can be used as a delicate pitoiwicope, to reveal 

 perfectly well the decay, the absorption, and the reflection, and 

 (less perfectly) the refraction of sound-bearing waves. A sketch 



is there given precisely the same as that which appears in Dr. 

 Tyndall's lecture (Fig. 6), wherein a sensitive flame is placed in 

 the conjugate focus of a pair of parabolic mirrors. This experi- 

 ment was shown at a lecture I delivered on January 3, 

 1S68, before the Dublin Royal Society. A copy ot my 

 paper in the Quarterly Journal of Science, and of the printed ab 

 stract of my lecture before tlie Dublin Society, I myself sent to 

 Dr, Tyndall a few days after they appeared, and if I mistake 

 not, drew his attention to these experiments. 



Since 186S I have so frequently shown to my own class and 

 to large audiences the reflection of sound by a sensitive flame, 

 that I have no doubt many of your readers will have been asto- 

 nished when they heard or read Dr. Tyndall's assertion which I 

 have quoted. Indeed, probably Dr, Tyndall himself will 

 be able to recall the^ foregoing facts, and will] gladly put ;his 

 memory right on this matter. 



\V. F. B.^RRETT 



Royal College of Science, Dublin, Jan. 19 



The Potato Disease 



Since October 1872 I have been growing potatoes, healthy 

 and diseased, mider test conditions, principally with a view to a 

 further insight into the winter and subterranean life of the 

 Pcroiiospora and also in the hope of meeting with the (to me) 

 apocryphal Artotrogus. The figures of ttie latter referred to by 

 Mr. Berkeley, I am well acquainted with, as I have engraved 

 them three times, once to illustrate Mr. Berkeley's own paper in 

 the Gctrdcneis Chronicle. I therefore well knew what to look 

 for in the corroded cellular tissue of my diseased potatoes. I by no 

 means wish to assert (or indeed asserted) that Volntelia ciliata is 

 positively the same with Montagne's Artotrogus, for I have never 

 seen a specimen of the latter, (I know no one who has except 

 Mr. Berkeley), and as far as I am aware] no one has met with it 

 since the time of its original publication between twenty and 

 thirty years ago. As no one now (including Mr. Berkeley) ven- 

 tures to suggest more than the " possible " or " probable " nature 

 of Artotrogus, my note was meant to suggest another reasonable 

 direction for future observation. 



In my experiments, I have from the first been forcibly struck 

 with the presence of Volutella with its mycelial threads, not only 

 outside and just within spent potatoes, but also within the 

 corroded cellular tissue. I have no doubt that the plasma of 

 Volutella is equally disorganising with the plasma of Pcroiiospora 

 itself, and that the threads belonged to the former plant I have 

 no manner of doubt, as I constantly traced young to mature spe- 

 cimens of Volutella from it, and that too from positions within 

 buried potatoes. The strong external I'esemblance between some 

 slates of Volutella and the figures referred to by Mr. Berkeley, 

 suggested to me that this "will o' the wisp " Artotrogus, might 

 perchance eventually turn out to be no other than some condition 

 of Volutella. 



So far from its being my desire to draw attention from Arto- 

 trogus, the paragraph in my first letter was written with a view 

 to draw attention to it. Berkeley himself always speaks doubt- 

 fully of its nature, and Carruthers, in his recent paper oaPerono- 

 spora, published by the Royal Agricultural Society, has not even 

 referred to it. 



Returning for a moment to the principal subject of my first 

 note, viz. the failure of the essays submitted in answer to the 

 offer of a prize on the part of the Royal Agricultural Society for 

 the best essay on the potato disease and its extirpation. In 

 Nature, vol. ix. p. 212, I observe that the committee are now 

 disposed to view the desired destruction of the potato disease 

 from a different standpoint, and propose to offer three prizes of 

 100/. to dealers, who are to send in a ton each of " disease- 

 proof" potatoes. 



It appears to me as unreasonable to advertise for a " disease- 

 proof" potato as for a "death-proof "man. .Surely all organised 

 bodies are liable to deviation from health, and though certain 

 organisms may be made (by art) to more or less throw off or 

 resist the attacks of disease, yet none can be said to be in them- 

 selves "disease- proof." As regards potatoes, I think I may say, 

 wuhout fear of contradiction, that at present no varieties whatever 

 are either proof against the Peronospora or able to resist its 

 attacks, neither is it at all likely that any such varieties will ever 

 arise. 



WORTHINGTON G. SMITH 



