Sept. 8, 1887] 



NATURE 



439 



For by the conditions obtained 6 is the same in both A 

 and B, Hence S = (- ) = r-J j , where r^ and r are the 



resistances of the two circuits. It is obviously unnecessary 

 to make the resistances, and the masses of liquids, equal, 

 but the equation is thus simplified. If a smaller mass of 



water, ;«, be taken, then S = - .v2\, thus increasing 



the delicacy of the method. 



Since in the adjustments a considerable amount of 

 time would be necessary to allow the calorimeters to 

 attain thermal equilibrium after each trial, the following 

 modification may prove more simple and more practi- 

 cal : — 



The calorimeter B is arranged so that by a switch-key, 

 C, the current can be diverted through a wire of exactly 

 equal resistance, b, so that the current is the same by 

 either path. The resistance from D to E is the same 

 either way. The key F is pressed down for a time, /, 



Fig. 2. 



until the needle is largely deflected ; then the current is 

 switched from B and passed through A alone, until the 

 needle is just brought back to zero, in total time, T. Then, 

 neglecting for the present the slight error due to cooling. 



in A ... ^M 



C2RT 



inB...^MS = 



C2R/ 



S - 1. 

 T 



Since T and / can both be made large, this should 

 give very accurate results. It is evidently especially 

 applicable to the measurement of the rate of increase of 

 specific heat with temperature, since the liquids may 

 have any initial temperature. 



In conclusion, I may say that I should not have pub- 

 lished this method in such an incomplete state, and 

 unsupported by experiment, but I noticed to-day (Sep- 

 tember 5) that Profs. Stroud and Gee intend to read a 

 paper before the British Association on " A Null Method 

 in Electro-Calorimetry," and it is possible this may refer 

 to a similar method. George N. Huntly. 



THE HESSIAN FL Y. 



T AM sorry to say that reports from correspondents ac- 

 -»• quainted with the attack of the Hessian fly show its 

 presence now in an almost continuous line along the 

 northern and eastern coast from Cromarty on the Moray 

 Firth in Scotland down to Kent. 



I have this morning received specimens of the pup art a 

 from the parish of Urquhart, in Morayshire, the most 

 northerly locality from which I have at present received 

 the so-called " flax-seeds." 



The amount of presence varies very much. In the locality 

 above mentioned (that is, the district from Aberdeen to 

 Cromarty), the traces of attack are reported as to be 

 found from 25 to 30 miles inland, but the injury slight, 

 not more than one straw in fifty being affected, and the 

 grain of fair quality. It is severe in some parts of Perth- 

 shire, and is found also in the eastern counties adjacent. 



In East Lothian, Haddington, and Berwickshire attacl 

 is only reported from a few places at present, and ii 

 Northumberland from one locality. 



Beginning again on the two sides of the H umber th 

 attack widens much in area as it is traced south. It passe 

 through Lincolnshire and Cambridgeshire, touching ai 

 easterly part of Northamptonshire, till it extends over th( 

 district commonly known as the eastern counties, includ 

 ing besides great attack in Hertfordshire, and some ii 

 Bedfordshire ; and it also occurs in Kent. 



In the southerly or westerly parts of England it occur 

 at Lymington and Petersfield in Hampshire, and to a con 

 siderable extent near the College of Agriculture, Downton 

 near Salisbury ; and I have one report of it from nea; 

 Bridgwater, and it also occurs at Goring Heath, Oxford 

 shire. 



The above localities are w.here I know of its presenc« 

 from specimens sent to myself, or, in a i&vj cases, fron 

 information given me by correspondents whom I know tc 

 be acquainted with the appearance of \.\\q pupartian, anc 

 the characteristics of the attack. 



It very likely may occur elsewhere, but I am only jus 

 giving a general sketch of extent of infested area fron 

 personal knowledge. 



It strikes me as a very curious point that the attacl 

 should so markedly cling to the sea-side, excepting in i 

 few isolated instances, or where the inland area is con^ 

 tinuous with the sea-side district. 



It is very satisfactory to observe that although the 

 season has been so altogether extraordinarily favourable 

 to various kinds of insects affecting corn-stems, yet thai 

 in very many instances reported to me the injury caused 

 to wheat by Hessian fly has been slight 



On this fact I venture to think we may ground a hope 

 that, either from the varieties of wheat which we use being 

 kinds suited to do what is called " resist " attack, or from 

 circumstances of our cultivation, we may find that oui 

 wheat at least does not suffer as much as in some othei 

 countries. 



Also the enormous prevalence of the two stem attacks 

 caused respectively by the corn sawfly {Ccphus pygmczus). 

 and by the dipterous fly, the Chlorops tceniopus (attacks 

 which far exceed in amount any which have been brought 

 under my notice as caused by these insects), give a hope 

 that the chmatal circumstances which usually prevail here 

 will have an effect in checking the attack of the Cecido- 

 niyia destructor, as well as the above-named crop pests, as 

 we see that all three kinds have been exceptionally 

 thriving in the exceptional heat and drought. 



It is unnecessary to point out to your highly informed 

 and thinking readers that the statements now appearing 

 of the Cecidomyia destructor having been a corn pest in 

 this country for many years have not the slightest 

 foundation. Eleanor A. Ormerod. 



THE BRITISH ASSOCIATION. 



Manchester, Tuesday Evening. 



ABOUT the success of the Manchester meeting there 

 seems to be only one opinion. In mere numbers — 

 the most popular gauge of success — it has by several 

 hundreds surpassed all former meetings ; the number of 

 tickets sold very closely approaches 4000. As a natural 

 result, the amount of money collected and available for 

 the purposes of research is unprecedentedly great, as will 

 be seen by the list of grants which have been allotted to 

 the various Committees. The great increase in attend- 

 ance over all former years is to a considerable extent 

 due to the large number of foreign visitors, who have 

 formed a marked and prominent feature of the present 

 meeting. In the proceedings of nearly every Section 

 the representatives of foreign science have taken an active 



