1006 



cuit can at any instant be broken by a touch of the observer, it 

 will be in his power, by a mere movement of his finger when the 

 object passes each wire of the transit telescope, to exhibit in the 

 impressed trace on the fillet a series of interruptions, peculiar to the 

 observation, mingled in their proper places with the series of in- 

 terruptions produced by the clock. As this can be done at each 

 station without impeding the similar operations at the other stations, 

 it is evident that several series of strictly comparable observations 

 may be recorded on the same fillet of paper ; one wire only being 

 necessary, and indeed only one being applicable. It then became a 

 question whether an analogous method of r#ording transits might 

 not be available for the observations of a single observatory, without 

 reference to the problem of determining terrestrial longitudes. For 

 this purpose it appeared best to reverse the relations of the clock 

 and galvanic current, so that the vibration of the pendulum should 

 make an impress upon a fillet or revolving disc. Practically, it is 

 found necessary to have another battery, another wire, another gal- 

 vanic magnet, and another style for making the impression corre- 

 sponding to each observed transit over a wire of the instrument : if 

 it happens that there are in the same observatory several instru- 

 ments where observations are to be comparable, by a proper arrange- 

 ment of wires all these observations may be recorded by means of 

 the same style. Numerical evidence is adduced to show that the 

 irregularity of transits thus observed is 'far less than that of transits 

 observed by the eye and ear; and there is no doubt that the 

 number of observations made in a given time may be very much 

 greater than that of observations made on the old system. On the 

 other hand, the after-labour of reading off* these graphical transits, 

 and converting them into numbers, will be considerable. I am not 

 aware that this method of observation has been used on our side of 

 the Atlantic, although I am able to assert that it has engaged the 

 attention of some of the English observers. Preparations are making 

 at the present time for trying it at the Royal Observatory at Green- 

 wich. It is proposed to record the transits taken with the new 

 transit circle, and those taken v/ith the altitude and azimuth instru- 

 ment, on the same recording surface. Numerous experiments have 

 been made in America by Mitchell, Walker and others, for deter- 

 mining with the aid of this system of record, the velocity of the 

 galvanic pulse through the ordinary telegraph wires. The inquiry 

 however is one of peculiar difficulty, and I am happy to find it is 

 engaging the attention of scientific men. 



Since our last meeting, the first volumes of Liebig and Kopp's 

 very interesting annual report on the progress of Chemistry and the 

 allied sciences have issued from the press. Full and complete as to 

 Chemistry, it is a very excellent index to the recent papers on phy- 

 sical science in the periodicals, and supplies that kind of informa- 

 tion so useful to a man, who, fully occupied with one engrossing 

 pursuit, is anxious to know something of what is passing around 

 him. Of the progress, ho*vever, of abstract mathematics it gives no 

 account : there, however, there has been progress also. Indeed, 



