462 Mr. J. Prestwich on Tables of [June 18, 



XXII. " Tables of Temperatures of the Sea at various Depths below 

 the Surface, taken between 1749 and 1868; collated and 

 reduced, with Notes and Sections." By JOSEPH PRESTWICH, 

 F.R.S., F.G.S. Received June 4, 1874. 



(Abstract.) 



This paper was commenced by the author more than twenty years 

 since, with a view to the geological bearing of the subject, but was for 

 some years unavoidably interrupted. It has now been brought down 

 to 1868, the date of the ' Lightning ' expedition, when the subject was 

 taken up by Dr. Carpenter, by whom it has since been so ardently and 

 ably carried on. Nevertheless, as Dr. Carpenter's work relates almost 

 solely to recent investigations, the author considers that there is yet con- 

 siderable interest attached to the work of the earlier observers from 1750 

 to 1868, though he feels that much of it is necessarily superseded by the 

 great and more exact work subsequent to 1868. He is aware that the 

 older observations have also not been deemed reliable on account of the 

 error caused by pressure on the thermometers at depths ; but this is far 

 from applying to the whole of them, as that error was taken into account 

 so early as 1836, if not before, and a large number of these observations 

 are equally reliable with the more recent ones, while the greater part of 

 the others admit of corrections which render them sufficiently available. 



In 1830, Grehler gave a list of 226 observations, and D'TJrville, in 1833, 

 tabulated 421 experiments according to depths. The present paper 

 contains a record of about 1300 observations, which are arranged accord- 

 ing to the degrees of latitude: 1st, for the northern hemisphere; 2nd, 

 the southern hemisphere ; 3rd, inland seas. They are all reduced to 

 common scales of thermometer, measure of depth, and meridian. Their 

 position is given on a map of the world, and the bathyinetrical isotherms 

 from the Poles to the Equator, based on the correct and corrected obser- 

 vations, are given in a series of ten sections. The author does not claim 

 for these observations the exact value, or the unity and completeness of 

 plan, of the more recent ones, while, as compared with them, the depths at 

 which they were made are on the whole very limited ; still they include 

 a few at great depths ; and as they extend over much ground that has 

 not been covered by the expeditions of the ' Lightning,' * Porcupine,' and 

 ' Challenger,' he trusts that these Tables may be of some use as couiple- 

 mental to these later researches, and as bringing together and reducing to a 

 common standard, observations scattered through a large number of 

 works and memoirs. At the same time, the author would observe that he 

 thinks it due to our many distinguished foreign colleagues who have been 

 engaged in the inquiry, and whose work seems but little known, that the 

 results of their researches should be understood in this country. Their 

 conclusions, which are in close agreement with those formed, entirely in- 



