#8 On a Uniform System of 



ceptions, the only instrument, in addition to those generally 

 used at sea, for which the conference has thought proper to 

 recommend a column, is that for specific gravity ; the cost 

 of this instrument is too insignificant to be mentioned. 



" The reasons for recommending the use at sea of the wet, 

 the white, and black bulb thermometers are obvious ; but with 

 regard to the thermometer with a bulb the colour of sea- 

 water, and the introduction on board ship of a regular series 

 of observations upon the specific gravity of sea-water, it may 

 be proper to remark that, as the whole system of ocean cur- 

 rents and of the circulation of sea-water depends in some de- 

 gree upon the relative specific gravities of the water in va- 

 rious parts of the ocean, it was judged desirable to introduce 

 columns for this element, and to recommend that observations 

 should be carefully made with regard to it, both at and below 

 the surface. 



11 With respect to the thermometer having a bulb of the 

 colour of sea-water, it is unnecessary to say more in favour 

 of its use on board ship than that the object is to ascertain 

 whether or no such observations will throw any light upon 

 the psychrometry of the sea, or upon any of the various inte- 

 resting phenomena connected with the radiation from the 

 surface of the ocean. 



" In bringing to a conclusion the remarks upon instruments, 

 the conference considered it desirable, in order the better to 

 establish uniformity and to secure comparability among the 

 observations, to suggest, as a measure conducive thereto, 

 that a set of the standard instruments used by each of the 

 co-operating Governments, together with the instructions 

 which might be given by such Governments for their use, 

 should be interchanged. 



" The object of the conference being to secure as far as pos- 

 sible uniformity of record and such a disposition of the ob- 

 servations that they would admit of ready comparison, the 

 annexed form of register was concerted and agreed upon. 

 The first columns of this form will receive the data which 

 the Government of the United States requires merchant ves- 

 sels to supply, in order to entitle them to the privileges of 

 co-operators in this system of research, and may therefore 



