402 SCIENTIFIC KECORD FOR J 882. 



tion, a new apparatus for determiuing the mechanical equivalent for heat, 

 and hopes to obtain its real value to within .001. {Nature, xxvi, p. 470.) 



The velocity of the motion of a ship through the water is ordinarily 

 given by the observations of some form of log. Froude and Burnet 

 invented an electric log, on which, however, Mr. Kelway has made 

 some decided improvements. The complete instrument has many and 

 important applications, and its adoption is to be encouraged. {Nature, 

 XXV, p. 585.) 



Professor Bramwell exhibited and explained the method of action of 

 a speed indicator in use on railroad trains. It consists of a drum, on 

 which are marked by two pencils the speed of the train and the condition 

 of the track. On a calm day a railroad train weighing 125 tons and 

 moving at the rate of 45 miles an hour ran 5 miles and 5 yards after 

 the steam was cut off. {Nature, xxvi, p. 495.) 



Professor Riicker j)resented the report of the committee on methods 

 of calibrating mercurial thermometers, in which, as the result of a long 

 investigation, it is concluded that labor is saved and equal accuracy 

 secured by the repetition of Gay-Lussac's method of correction, instead 

 of the employment of more elaborate schemes. {Nature, xxvi, p. 458.) 



G. J. Symons, after relating the history of progress in our knowledge 

 of the subject of diminution of rainfall with elevation, explained the 

 theory of Stanley Jevons — that it depended on eddies about the gauge 

 itself, and gave an account of the comparative researches of Mr. Roger 

 Field, who took the matter up a few years ago, and who has shown (1) 

 that the ratio of the rainfall on the tower to the rainfall on the ground 

 depends on the force and direction of the wind ; (2) that when there is 

 no wind the rainfall on the tower is about the same as the rainfall on 

 the ground; (3) that when there is wind the amount of rain falling on 

 the tower will vary on different portions of the tower, the portion near- 

 est the point at which the wind strikes the tower receiving less rain 

 than falls on the ground, and the portion farthest from the point at 

 which the wind strikes the tower receiving the same or more rain than 

 falls on the ground ; (4) that the excess of rain falling on the portion 

 of the tower farthest from where the wind strikes will, to a large ex- 

 tent, compensate the deficiency of rain on the portion nearest to where 

 the wind strikes, but whether to a sufficient extent to make the average 

 amount of rain falling on the tower equal to that falling on the ground 

 cannot be determined from these experiments. From these conclusions 

 it is clear that if the building be flat and large, the fall in the middle 

 of the roof ought to be nearly the same as on the ground, and in two 

 instances this is so — first at Messrs. Marshall's factory at Leeds, and 

 secondly, at Mr. Dine's, on a roof with 5,000 square feet of area. Thus 

 finally experimental evidence has corroborated the views of Mr. Stanley 

 Jevons, given above. {Nature, September, 1881, xxiv, p. 401.) 



One of the features of the International Electrical Exhibition and 

 Congress at Paris in September, 1881, was the meteorograph of M. 



