268 Mr. T. Dobson on the Storm-trucks of 



So I consider the excitement of induction currents in liquids 

 not metallic as proved; and as far as I can judge, they arc pro- 

 portionate in strength to the conducting power of the body in 

 ■which they are generated. In the dilute sulphuric acid they 

 were of course stronger than they appeared by the deflection to 

 be, because they had first to overcome the contrary deflection 

 which the direct action of the magnet was able to produce ; the 

 sum of the two deflections, in fact, expressed the force of the 

 induced current. Whether the conduction by virtue of which 

 they occur is electrolytic in character or conduction proper I can- 

 not say. The present phfenomena do not aid to settle that ques- 

 tion, because the induced current may exist by either the one 

 or the other process. I believe that conduction proper exists, 

 and that a very weak induction current may pass altogether by 

 it, exerting for the time only a tendency to electrolysis, whilst a 

 stronger current may pass, partly by it and partly by full elec- 

 trolytic action. 



I am, my dear friend. 



Ever most truly yours, 



M. Faraday. 



XXXIX. On the Storm-trucks of the South Pacific Ocean. By 

 Thomas Dobson, B.A., Head Master oj the High School of 

 Hohart Toivn, Van Diemen's Land. 



[With a Plate.] 



THE law of the westerly progressive motion of tropical cy- 

 clones has now been Avell established in all the regions 

 sufiiciently frequented by large ships to aflbrd several trust- 

 worthy observations of the same storm ; as in the West Indian 

 Seas, the South Indian Ocean, the Bay of Bengal, and the 

 China Sea. For the South Pacific Ocean not a single storm- 

 track is given in any work on cyclonology. The results of the 

 researches that I have undertaken with a view to supply this 

 deficiency have induced me to doubt the generality of the law of 

 westerly progression, and to suspect the existence of an import- 

 ant anomaly in the region rci'erred to ; for while they do not 

 j^rcsent one exception to the law of rotation in the order N.E.S.W., 

 they all tend to show that in the South Pacific Ocean cyclones 

 travel at first to the eastxvard, and then towards the south-east 

 and south, moving off" finally towards the south-west. The mean 

 storm-track of the South Pacific Ocean is therefore exactly the 

 reverse of that of the South Indian Ocean, instead of being 

 similar to it in position, as is always supposed by writers on 

 cyclonology. The following is an abstract of the facts from 

 which this conclusion has been deduced. 



