The Integral Weight of Water. 269 



a signal, on which B would read his aneroid, while C started 

 both his chronographs. A would first note the height of the 

 deck by marks on the ship's side ; and, if need be, read a 

 simple clinometer to allow for the roll of the ship before 

 entering the records of his assistants. When the crest reached 

 the bow, A would give another signal for C to stop one chro- 

 nograph. In the trough, B would read his aneroid, while A ' 

 noted the height of the water ; and, finally, as the next crest 

 came on, B would read his aneroid, C would stop his second 

 chronograph, while A noted the height of the water and entered 

 all the records. 



By this means, and with a careful selection of tolerably 

 undeformed waves, I think that the measurements of undula- 

 tions could be much more satisfactorily obtained than hereto- 

 fore ; and I only regret that the means at my disposal did not 

 enable me to do more towards this important line of research. 



Summary. 



The results of this paper may be summarized as follows: — 



Several sets of observations between New Zealand and 

 Cape Horn, with an aneroid barometer and chronograph, gave 

 for the largest waves a height of 46 feet, a length of 765 feet, 

 a speed of 47 miles an hour, and a time-period of 16*5 seconds. 



As nothing but the ordinary heavy weather of these lati- 

 tudes was experienced, it is certain that waves must sometimes 

 attain a height of at least 60 feet. 



Really big seas are of very rare occurrence. 



The great discrepancies in the observed elements of waves 

 given by different observers is doubtless due to the varying 

 lengths of every series of undulations, which therefore always 

 make a more or less confused sea. 



XXXII. The Integral Weight of Water. 

 By T. Sterey Hunt, LL.D., F.R.S* 



IN a paper on Chemical Integration, published in the 

 American Journal of Science for August 1887, and 

 reprinted in the ' Chemical News ' of September 23 and 30, 

 it was said that, in comparing the densities of liquid and solid 

 bodies with those of known gaseous species, such as water- 

 vapour and carbon dioxide, " or in the last analysis, with the 

 density of the hydrogen unit .... we get the specific gravity 

 of these bodies, the dyad integer of hydrogen at 0° and 760 

 millim. (H 2 = 2'0) being unity." Subsequently, in a paper 



* Communicated by the Author. 



