34 REPORT—187 4: 
Gramme machine through a certain number of smaller machines, placed at points 
more or less distant. 
Experiments now in progress will, it is hoped, prove to the British Association at 
its next Meeting how far these ideas are practicable and may be useful; these expe- 
riments will, to use the language of the mechanical theory of heat, show the eco- 
nomic coefficient of the system in question. 
The first experiment may be slightly modified as follows :— 
In the circuit of the two Gramme machines insert a platinum wire; stop machine 
B and turn machine A: the platinum wire heats, and indeed becomes red-hot by 
the passage of the current from A; machine B remains quiescent, having heen 
stopped; but if the stoppage be removed it will be seen to move immediately, and, 
immediately also, the platinum wire ceases to be red. 
The second experiment presents, I think, a sufficiently striking example of the 
equality of mechanical action and heat ; besides which it realizes in a new manner 
an experiment described by Helmholtz in his paper on the “ Conservation of Force,” 
Helmholtz operated with a pile which turned an electromagnetic machine; a gal- 
vanometer was placed in the circuit, and its deviation was seen to diminish in pro- 
portion as the rapidity of the machine increased ; he showed that the deviation of 
the galyanometer would be xz? at a certain rapidity of the machine. We shall show 
that in our experiment, the two machines being supposed to be alike, the deviation 
of the galvanometer and the intensity of the current would become ni/ when the 
rapidity of the two machines is the same. 
inally, our second experiment may also be looked at from another point of view ; 
it affords an illustration of Neumann’s principle, which may be described in the 
following words :—‘ Eyery effect produced by an electric current inyolyes a dimi- 
nution of the intensity of such current.” 
We observe, in conclusion, that so extensive and general a principle cannot be 
proved by experiment, any more than the principle of action being equal to reaction ; 
with truths of this nature we can but claim to accumulate demonstrative verifica- 
tions, and it is without doubt interesting to search for such as may strike the mind 
of the student. 
[M. Breguet’s instruments referred to in this abstract were exhibited to the Mem- 
bers of the Association on Tuesday, August 25, after the Sections were closed. The 
paper was not read at the Meeting, but the abstract is printed with the authority of 
the Council.—G, G.] 
METEOROLOGY. 
On the Cause of the Progressive Motion of Cyclones, and of the Seasonal Varia- 
tions in their Paths. By Isaac Asuz, A.B., M.B., T.0.D. 
Dr. Ashe pointed out the importance of arriving at a correct theory regarding the 
causes of the onward progress of cyclones over the face of the globe, on account of 
the light which would thereby be thrown on the question of seasonal variations in 
their paths, such as had been observed by Captain Fryers, R.E., in the South- 
Indian Ocean. <A correct theory would serve to indicate the line of research in 
future observations directed towards this point. Seasonal variations of path would 
be due to special modifications of the more constant forces governing the paths and 
progress of cyclones, such special modifications being dependent on the changes 
induced in the action of the forces causing such progress in consequence of changes 
of season. The general law would depend on the more constant, and the seasonal 
variation on the less constant elements of these forces. The more constant elements 
would be those inherent in the cyclone itself; the less constant elements would be 
those depending on the prevailing winds of the zone and their seasonal variations. 
The varying elements were better known than the fixed, though perhaps their 
causal relation was not recognized from want of acquaintance with the fixed ele- 
ments and more constant forces inherent in the cyclone itself, on which the onward 
progress of the cyclone depended. 
