Royal Society. 91 



when the thermometer had nearly reached the boiling point, and 

 the action of the battery was at its maximum, a sudden cessation of 

 its action would take place ; and this suspension of power would 

 continue for hours, provided the high temperature were maintained. 

 On turning off the steam, and quickly cooling the apparatus, the 

 action would return as suddenly as it had ceased, though, generally, 

 not to the full amount. On closely examining the voltameter, on 

 these occasions, it was found that the current was not wholly stopped ; 

 but that there existed a small residual current. This residual cur- 

 rent was observed to be often directed in a course opposite to that 

 which had before prevailed ; and it was, in that case, the excess of 

 a counter current, arising from a force which was acting in the 

 contrary direction. The author found that variable currents might 

 be produced, under ordinary circumstances, from the separate single 

 cells of the battery when the whole series is connected by short 

 wires. He proved by a series of experiments that the deoxidation 

 of the oxide of copper by the hydrogen is not the exciting cause of 

 the secondary currents j but that when the course of the main cur- 

 rent of the battery is obstructed by causing it to pass through the 

 long wire ofa galvanometer, or througbthe electrolyte of a voltameter, 

 the course of the secondary current from each separate cell is always 

 normal, or in the same direction : when, on the other hand, the 

 battery-current is allowed to flow with the least possible resistance, 

 as by completing the main circuit by a short wire, the secondary 

 current of the separate cells is in the opposite direction. Hence 

 the resistance may be so adjusted as that the secondary current shall 

 altogether disappear, or alternate between the two directions. 



The remainder of the paper is occupied with the detail of ex- 

 periments made with a view to ascertain the effects of different degrees 

 of resistance to the voltaic currents under a great variety of cir- 

 cumstances. 



April 20. — A paper was read in part, entitled, " Observations 

 taken on the Western Coast of North America." By the late Mr. 

 Douglas j with a report on his paper ; by Major Edward Sabine, 

 R.A., F.R.S. Communicated by the Right Honourable Lord Glenelg, 

 one of His Majesty's Principal Secretaries of State, F.R.S., &c. 



April 27. — The reading of Mr. Douglas and Major Sabine's pa- 

 per, was resumed and concluded. 



In the report prefixed to this paper, Major Sabine states, that 

 Mr. Douglas was originally a gardener, and was, in the year 1833, 

 recommended by Sir William Jackson Hooker to the late Mr. Joseph 

 Sabine, who was then Secretary to the Horticultural Society of Lon- 

 don, as a fit person to be employed by the Society in selecting and 

 bringing to England a collection of plants from the United States 

 of America. Having accomplished this mission to the complete 

 satisfaction of his employers, he was next engaged on an expedition 

 having similar objects with the former, but embracing a much larger 

 field ; namely, the tract of country extending from California to 

 the highest latitude he might find it practicable to attain on the 

 western side Qt' the Rocky Mountains. Anxious to render to geo- 



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