8 8 ■ TEE DEPTHS OF THE SEA. [chap. m. 



which had not previously been taken in the British 

 seas. 



Here the Miller-Casella thermometers were tried 

 for the first time and compared with those of the 

 ordinary construction. The minimum recorded by 

 one of the former was 5°-2 C, while that recorded by 

 one of the best ordinary instruments of the Hydro- 

 graphic Office pattern was 7°'3 0. As this difference 

 of 2° 0. was almost exactly what the results of the ex- 

 periment previously made had indicated as the effect 



Fig 9. — ^'cr/yuH f7-M7ens, Kboyek. Young. Twice the uatural size. (No. 7.) 



of a pressure of 1 ton on the square inch, which is 

 about equal to the pressure of a column of sea-water 

 of 800 fathoms, this close coincidence gave great 

 confidence in the practical working of the protected 

 instrument, a confidence which all subsequent ex- 

 perience has fully justified. 



Mr. Gwyn Jeffreys and his companions next pro- 

 ceeded to examine the sea-bed between Galway and 

 Porcupine Bank, a shoal discovered during one of 



