B. TERRESTRIAL PHYSICS AND METEOROLOGY. 121 



four and one-half times that of water. Colonel James has 

 by a similar method deduced 5.316, and Airy finds 6.565. 

 Cavendish, by measuring the attraction of a large mass of 

 lead for a small ball, obtained 5.48 ; Reich, by a similar meth- 

 od, obtained respectively 5.44, 5.49, 5.58. Baily's result was 

 5.67, and was obtained by the same method with great care 

 and labor. None of these results seem to be so accurate as 

 that just published by Messrs. Cornu and Bailee, who have 

 also recalculated the observations of their predecessors, and 

 explained away some of their discordances. Their own ap- 

 paratus was not different in principle from that of Cavendish, 

 Reich, and Baily, but was a great improvement upon these 

 in employing balls of lead instead of quantities of mercury, 

 thus enabling them to reduce the length of the arm of the 

 torsion balance. They also eliminated the influence of any 

 electricity that might be present by constructing the entire 

 apparatus of metal. The method adopted by them of re- 

 versing the attraction of the sphere of mercury was pecul- 

 iarly ingenious and advantageous, and consisted in connect- 

 ing an empty glass globe on one side of the table with the 

 filled glass globe on the other side by means of a tube 

 through which the mercury could be made to flow easily from 

 one globe to the other, and they also introduced the electro- 

 chronographic method of registration. The result that they 

 announce is for the mean density of the earth either 5.56 or 

 5.50, the former probably being nearer the truth. They also 

 correct Baily's computations for the attraction of the lever, 

 which he had himself not properly appreciated, and had then 

 deduced from his observations 5.55 as the result of his own 

 experiments. Giving a greater weight to the recent observa- 

 tions of Cornu, we may deduce from these and Baily's results 

 the figure 5.56 as representing very nearly the true mean 

 density of the earth. 6 B, 1873, 954. 



THE ANTI-GULF-STEEA:M IX THE WEST INDIES. 



In a recent letter of the English consul-general at Havana, 

 attention is called to the remarkable destruction of vessels 

 during the months of September to December, 1872, along 

 the northern coast of Cuba. Although there is a tendency 

 to unduly attribute the loss of vessels to unknown cur- 

 rents and to other mysterious causes, yet the consul-general 



F 



