74 APPENDIX TO REPORT ON OYSTER CULTURE 



Owing to the circumstance already alluded to at the commencement 

 of this report, I have not made much use of the observations on the tem- 

 perature of the sea in October, 1868, but as at the following stations the 

 observations are stated to have been made at noon, except one, which I 

 include on account of the air, temperature having been exceptionally 

 observed, it appears desirable to compare the results with those contained 

 in the foregoing table. 



Mean Temperature at Noon in October, 1868. 



At sea. Near shore. Air. 



Ballyglass (Belmullet), 52-0 50 51*2 



Carrickfergns, 50-0 48-8 



Carlingford (Cranfield Point), 534 53-6 



Filey (Yorkshire), - 48-5 



Ramsgate, 554 54 -2 



As these results are obtained from observations made during the last 

 three weeks of October, they should be lower than the means derived 

 from the whole month and intermediate between these and the results 

 for November. Bearing this in mind, they may be considered as confir- 

 matory of our general results, and especially of the superior temperature 

 of the southern and western coasts of the British isles. They also show 

 that the temperature of the sea in deep water during October is a little 

 greater than near the shore, a circumstance that might be anticipated 

 for the late autumn and winter months. 



The blue lines on the map representing the distribution of mean annual 

 temperature at the surface of the sea, are laid down partly from the re- 

 sults in Table III., and from indications in Maury's charts of ocean tem- 

 peratures, published by the Government of the United States. The 

 dotted lines along part of the coast in the same map represent the distri- 

 bution of temperature at noon in July, deduced from the results in our 

 first table. 



It appears from Table III. that the mean temperature of the sea during 

 the winter months was decidedly in excess of that of the air at the time 

 when the observations were made, and this excess was maintained even 

 in the mean annual temperatures, thus confirming the proposition already 

 stated as to the important heating influence of currents derived from the 

 Gulf Stream. The difference between the air and water temperatures, 

 during the months of May, June, and July, in this table, may be instruct- 

 ively compared with the corresponding differences derived from the noon 

 observations in 1869, as shown herewith. 



Table of Differences of Mean Temperatures of Air and Sea. 



May. June. July. 



Castletownsend, 



+04 



+ 0-5 



+ 04 



Bunown, 



—2-3 



—1-3 



—1-9 



Courtown, 



—0-7 



—0-9 



—2-3 



Donaghadee, 



+0-5 



+3-3 



+ 1-8 



Cushendall, 



4-14 



+3-2 



+ 14 



Portrush, 



-02 



+ 1-0 



—1-0 



Means, —0-25 +1'0 —0*3 



As before, the + signifies that the air was warmer than the water, 

 and the sign — that water was warmer than the air. This table shows 

 in a remarkable manner the influence of heat-bearing currents during 

 the months when sunshine is most powerful. 



As the object of the present inquiry is, the determination of the con- 

 ditions of sea- water climate in connexion with the development of a cer- 



