Jan. lo, 1884] 



NATURE 



239 



<in observations extending over a perio i of six consecutive 

 months; with soil temperatures, a series of observations 

 embracing a similar period ; with the normal condition 

 (f vegetable structure with reference to cell contents ; 

 and with "peach yellows," a disease attacking peach 

 trees. To do justice to any one of these memoirs would 

 really require a separate notice, but the mere mention of 

 them will serve to indicate some of the channels into 

 M-hich the energies of this new centre of research are 

 being directed. In connection with the meteorological 

 work, however, it is worth noting that daily bulletins 

 were issued, the predictions being made for twenty-four 

 hours from noon to noon. The whole number of predic- 

 tions made was 210, of which only rg per cent, proved 

 incorrect, so that the bulletins came to be depended upon 

 and ser\-ed a most important purpose for the time during 

 which they were issued. All the reports are printed in 

 .in attractive form, and special pains appear to have been 

 bestowed upon the diagrams and coloured plates. 



To the names that have already been mentioned it is 

 necessary to add that of Mr. Henry E. Alvord, who 

 has undertaken the duties of general manager. Mr. 

 Alvord's name is already familiar to agriculturists on this 

 side of the Atlantic, particularly in connection with Ame- 

 rican dairy farming, and his association with Houghton 

 Karm is another guarantee, if one were needed, of the 

 t'loroughly business-like manner in which the new e.xperi- 

 ment station is to be conducted. 



From this brief sketch it will be seen that there exist at 

 Houghton Farm potentialities whose development can 

 hardly fail to exercise considerable influence on the agri- 

 cultural practice of the future. Those who have studied 

 tlie Rothamsted results will be glad to compare with them 

 llie results deduced from the Houghton Farm experiments, 

 and each station will be benefited by comparing notes 

 with its friendly rival, while the valuable work which j 

 English agriculturists associate with the names of Lawes, 

 (".ilbert, Pugh, Masters, and Warington will, it is to be 

 hiiped, find a parallel in the discoveries we shall con- 

 fidently look fur from the transatlantic station. 1 ntention- 

 ally planned, in many details, upon the same lines as 

 Rothamsted, there ij one point in which the new station 

 specially resembles its English prototype, and it is con- 

 t:uned in the words, " Visitors are always welcome at 

 Houghton Farm." W. Fream 



advantages over those of the ordinary quadrant electro- 

 meters. In these, when the quadrants consist of four 

 pieces of flat brass borne each on an insulating pillar, it is 

 difficult to set them so that they shall be all exactly in 

 one plane ; and when, as in some of the more delicate 

 instruments, the quadrants are made of a hollow box slit 

 into four parts, there is found the further difficulty of 

 arranging the quadrants so that the needle can be taken 

 out and replaced. These difficulties are, to a large extent, 

 obviated in Dr. Edelmann's form of instrument ; for the 

 inner surface of the cylinder, which constitutes the four 

 quadrants, can be turned perfectly true after the quadrants 

 have been screwed to the ebonite rings ; and there is no 

 difficulty at all in lowering the needle into the cylindrical 

 cavity within the quadrants, or in lifting it out. The 

 needle itself is of the form shown in Figs. 2 and 3, and 



A 



EDELMANN'S ELECTROMETER 

 MONGST the many forms of electrometer that 



derive their origin from the quadrant electrometer 

 of Sir William Thomson is that of Edelmann, which is 

 very extensively used in the physical laboratories of the 

 Continent. Dr. Edelmann, whose name it bears, is not 

 only proprietor of workshops in Munich, which are 

 r.ipidly winning renown for the excellence of the instru- 

 ments which they turn out, but also holds the post of 

 Jirivdt-docent in the Polytechnicum of Munich. 



In the parent instrument of .Sir \V. Thomson, and in 

 most of the modifications of that instrument which go by 

 the names of Branly, Kirchoff, Mascart, &c , the quadrants 

 are literally four quadrants cut from one plane circle; 

 and in most of these instruments the needle is of the flat 

 dumb-bell or lemniscate form which Sir W. Thomson 

 hi nself gave to it. Dr. Edelmann has, however, taken a 

 departure in quite another line, his instrument being very 

 ajipropriately named the "cylinder-quadrant"' electro- 

 meter. The three accompanying figures show the essen- 

 ti d parts of the instrument. The quadrants, marked 

 r. in Fig. i, and a, b, e, d in Fig. 2, are formed by 

 taking a metal tube, furnished with flanges above and 

 below, and slitting it into four parts by four equidistant 

 cnts parallel to the axis of the tube ; the four pieces being 

 then set in their proper places by being screwed to two 

 Tmgs, R and S, of ebonite. This arrangement has some 



consists of two portions of metal (w \v) cut from a 

 cylinder, united above and below, and hung by a single 

 fibre of small torsion from an adjustable head, F, above. 

 A mirror, .f, is attached above the needle, and a platinum 

 vane, P, below it dips into a vessel, T, containing sulphuric 

 acid. To give directive force to the "needle" a small 

 magnetic needle, n s, is attached to it. This device was 

 indeed used in some of Sir W. Thomson's early instru- 

 ments, though subsequently abandoned in favour of the 

 bifilar suspension usually adopted. It is of course under- 

 stood that the opposite pairs of quadrants are, as usual, 

 connected together. Electrodes, A, b, pass through the 

 metal plate, 11, which covers the instrument, and are con- 

 nected with the quadrants as shown in Fig. I. An outer 

 jar of glass surrounds the instrument and is fixed to the 

 under side of the plate M by a bayonet point. The plate 

 11 itself is very substantial, and is provided with three 

 levelling screws which rest in V-grooves in a strong ring- 



