Dec. 25, 1879] 



NATURE 



189 



The Transactions of the Cumberland Association for the 

 Advancement of Literature and Science for 187S-9, is a volume 

 of 340 pages, edited by the Rev. J. Clifton Ward. Among the 

 numerous excellent papers contained in the volume are the 

 following: — An ethnological paper by Mr. R. S. Ferguson, 

 entitled "The Formation of Cumberland;" "Our Summer 

 Visitor?," a local natural history article, by Mr. T. Duckworth; 

 BD interesting paper on the Dipper (Cinclus aquaticus) by Mr. 

 William Duckworth; "The Entomology of the District," by 

 Mr. George Dawson; "The Great Lake, Lagoon or Bay of 

 Triton," by Mr. B. A. Irving ; " List of Cumberland Birds in 

 the Carlisle and Keswick Museums," by Mr. George Dawson 

 and the Rev. J. Clifton Ward. 



PHYSICAL NOTES 



Some useful observations on the action of safety valves on 

 boilers hive been recently communicated to the Vienna Academy 

 by Herr voa Burg (November 13). Among other things it is 

 proved that the authoritative directions given in different coun'ries 

 as to the size of safety valves are not at all adequate, and are 

 based on erroneous conceptions. As to the cause of the small 

 amount of lifting of the valve during escape of steam (seldom 

 over § mm.), the author at first supposed a vibratory motion of 

 the valve, but further study and experiment led him to the hypo- 

 thesis that the steam jets, in lifting the valve, do not begin to 

 move from its middle point, but from the periphery of a circle, p, 

 out to the circumference of the valve of radius r ; so that the 

 pressure of steam on the under surface of the valve is composed 

 of two parts, of which the inner, or aerostatic, is produced by the 

 solid steam-cylinder of radius p, and the outer or weak aero- 

 ■■•lie part, by the external hollow cylinder of r-p thickness of 

 wall. The pha-es of development of steam tension, and other 

 topics, are also investigated. 



A simple method of perforating glass with the electric spark 

 is described by M. Fages in a recent number of La Nature. The 

 apparatus required consists (1) of a rectangular plate of ebonite, 

 its size, for a coil giving 12 ctm. sparks, about 18 ctm. by 12 ; 

 (2) of a brass wire passing under the plate and having its pointed 

 end bent up and penetrating through the plate (not further). 

 This wire is connected with one of the poles of the coil. A few 

 drops of olive oil are placed on the ebonite plate about the point, 

 and the piece of glass to be perforated is superposed, care being 

 taken not to imprison any bubbles of air. The olive oil perfectly 

 accomplishes the object of insulating the wire. One has then 

 only to bring down a wire from the outer pole of the coil, On the 

 piece of glass, above the point of the lower wire, and pass the 

 spark. By displacing the glass laterally, for successive sparks, it 

 is easy to make a close series of holes in a few seconds. 



It has often been queried what might be the reason of the 

 high specific heat of water. Some light has been thrown upon 

 this problem by the recent research of a Russian gentleman of 

 the name of Beketoff, upon the specific heat of the hydrogenium- 

 alloy of palladium, and upon that of the hydrogen in the alloy. 

 The specimen examined by M. Beketoff contained about half per 

 cent, of hydrogenium to ninety-nine and a half of palladium. 

 On examination by careful calorimetric measurements the specific 

 heat of hydrogenium was found to be not less than 5 - SS ; which 

 though probably requiring correction is certainly not greater than 

 the true value. The value should be somewhere about 6'4 by 

 the law of atomic heat of Dulong and Petit. 



A vibration micrometer for ascertaining with precision the 

 amplitude of vibrations of tuning-forks and other sounding 

 bodies was recently shown in l'aris by M. Mercadier. It is an 

 extremely simple device and can be applied to any vibrating 

 bodies except such as possess very small mass. A small piece of 

 thin w hite paper bearing one fine black line is affixed to the body 

 whose vibrations are to be mea s ured. If this line is upright, it 

 will, w hen caused to vibrate, present the appearance of a pale 

 grey parallelogram, the persistence of the visual impression being 

 perfectly definite for the extreme positions of the vibration. To 

 ascertain the amplitude of the vibration, all that is necessary is 

 to measure the apparent width of this minute parallelogram in a 

 direction at right angles to the axis of symmetry of the oscilla- 

 tions. To do this with still greater precision, M. Mercadier pro- 

 poses to set the line not perpendicular to the direction of the 

 movement, but inclined to it at a small angle, and marks also 



upon the paper a fine scale of lines parallel to the direction of the 

 movement and di-tant from one another by equal distances of 

 one millimetre. The width of the narrow parallelogram is thus 

 read off along a straight line, which makes a small angle with its 

 sides, thus giving the quotient of the amplitude sought by the 

 tangent of a small angle. Using this method, M. Mercadier 

 showed that the vibrations of a tuning-fork "interrupter," 

 vibrating automatically under the influence of an electro-magnet, 

 may be regulated so as to be greater or less at will by adjusting 

 to a greater or less distance from the prongs of the fork the 

 electro-magnet which maintains the vibrations. 



Prof. Tait has abandoned the enticing speculation that the 

 thermal conductivity of metals is inversely proportional to their 

 absolute temperature, a conclusion to which his earlier experi- 

 ments on the conductivity of iron seemed to point. Many metals, 

 indeed, present the opposite case, their conductivity increasing 

 with the temperature. 



A means of comparing the intensities of lights of different 

 colours has long been desired. Until quite lately there did not even 

 exist a means of measuring the relative intensity of two lights of 

 the same given colour. M. Gouy has been investigating the 

 latter point by the aid of a particular photometer, and by flames 

 of constant brilliancy produced by the combustion of a homo- 

 geneous mixture of coal-gas with air impregnated with saline 

 powders. The photometer resembles in general appearance a 

 two-prism spectroscope, having also an auxiliary collimator with 

 a fixed lamp to serve as a standard light. In place of the usual 

 eye-piece of the instrument a second slit is placed. By this 

 means any one ray can be separately observed, and its intensity 

 compared with the intensity of the same ray from the standard 

 source. M. Gouy states that this slit eye-piece arrangement 

 is capable of such accurate adjustment that each of the two 

 D-lines can be separately examined and its intensity measured. 



Marat, the notorious hero of the first French revolution, the 

 same who met his death at the hands of Charlotte Corday, was 

 the author of several important essays on electricity. This fact, 

 which is not generally known, was recently brought to notice by 

 Mr. A. J. Frost, who is editing the catalogue of the Ronalds 

 Library. Most of Marat's vorks were written between 1779 

 and 1785, and several of them were translated into German, 

 Marat was not the only one of the prominent figures of the time 

 who worked in physical science. Arago, though his fame does 

 not re.it upon his political achievements, once enacted the 

 chief part in the crowning of the statue of Liberty. "Citizen" 

 Charles was as famous amongst the revolutionists as for his 

 scientific attainments. Robespierre wrote an article on the 

 lightning-conductor for the Journal ties Savants ; and last, but 

 not least, Napoleon Buonaparte on many occasions dabbled in 

 scientific lore, and was the liberal patron of men of science. 



Edison's telephone has, it is said, been successfully used over 

 a line of 2,000 miles in length. A hunting party in Nebraska 

 were thus enabled to converse with perfect distinctness with 

 their friends in Pennsylvania, vid Chicago and the Western Union 

 Telegraph Company's line. 



GEOGRAPHICAL NOTES 

 The Neapolitans are preparing to fete Prof. Nordenskjold, 

 who intends staying a short time in Southern Italy before return- 

 ing overland to Sweden. The Vtga arrived at Galle on the 

 16th inst. We have rereived from Hongkong an account of the 

 reception given to Prof. Nordenskjold and the officers of the 

 Vega, on arriving at that Eastern limit of the British Empire. 

 At the close of an official banquet at Government House, 

 Governor Hennessy congratulated Prof. Nordenskjold and 

 his staff in the warmest terms. "We behold," he said, "as 

 it were in this remote outpost of Europe, the writing of the 

 last words in the last chapter of heroic maritime discovery." 

 Captain Palander brought down to the drawing-room the 

 actual charts he had used during the voyage, and throughout the 

 evening they were inspected by the Governor's guests with 

 great interest. The charts were Russian ones, and one of the 

 minor results of the expedition has been the establishment of the 

 fact that they are not accurate, inasmuch as a great deal that 

 was put down as land was actually sailed over by the Vega. The 

 route wa, marked in red ink and pencil and showed these inac- 

 curacies. Some specimens of the plants from the region where 

 the Vega was so long bound up in the ice and photographs of the 

 natives were also on the drawing-room tables. We understand 



