481 



out any corresponding expenditure ; or we could theoretically have a 

 means of perpetually obtaining mechanical work out of nothing, 

 unless it were the case that greater cold is required to freeze water 

 into ice on the stressed crystal than on a crystal free from stress. 

 Hence we must suppose that a greater degree of cold will be required 

 to cause the stressed crystal to grow. The reasoning just given has 

 been for brevity stated somewhat in outline ; but I trust the full 

 meaning can readily be made out, and that what has been said may 

 suffice. 



I wish now to suggest as an important subject for investigation, 

 The Effect of Change of Pressure (hydraulic pressure) in changing the 

 Crystallizing Temperatures of Saline or other Solutions of given 

 Strengths, as I feel sure that such effect must exist, but am not 

 aware that it has been hitherto discussed or experimented on, and 

 as it is intimately connected with the matters under consideration in 

 the present paper and with subjects discussed in previous papers, 

 which I have submitted to the Royal Society, on Ice. 



II. "Determination of the Magnetic Declination, Dip, and 

 Force, at the Fiji Islands, in 1860 and 1861." By Colonel 

 WILLIAM JAMES SMYTHE, of the Royal Artillery. Com- 

 municated by General SABINE, P.R.S. Received October 

 23, 1861. 



[Note by the Communicator. Colonel Smythe is known to mag- 

 neticians as having been Director of the Magnetic Observatory at Sr, 

 Helena from 1842 to 1847. Being about to proceed, in December 

 1859, on a Government Mission to the Fiji Islands, which would 

 require his residence there for some months, he addressed a letter to 

 the Council of the Royal Society expressing his readiness to make 

 any scientific observations that might be suggested to him as likely 

 to be useful in a part of the globe hitherto so little known. The 

 Council directed that the Committee of the Kew Observatory should 

 be informed of the opportunity thus offered of obtaining a reliable 

 determination of the present values of the magnetic elements at the 

 Fiji Islands ; and Colonel Smythe was in consequence supplied with 

 the necessary instruments from that establishment. 



In communicating to the Society this paper, containing the results 



