352 On Mr. Talbot's Proposed Method of sounding the Ocean, 



extremity of the abdomen, £th of an inch ; length of the ce- 

 phalothorax T \j ; breadth -~ z ; breadth of the abdomen T ^ ; 

 length of a posterior leg f- ; length of a leg of the third pair \, 



This species, which appears to have a closer affinity with 

 the Agelena? than with the spiders of any other genus, occurs 

 in the woods at Oakland ; it is found occasionally under stones, 

 but is by no means common. I am at present ignorant of its 

 ceconomy, and the male has not yet fallen under my observa- 

 tion. 



Oakland, Denbighshire, Sept. 30, 1833. 



LVIII. On Mr. Talbot's Proposed Method of ascertaining the 

 greatest Depth of the Ocean, 



To the Editors of the Philosophical Magazine and Journal, 

 Gentlemen, 

 "LTAVING been absent from England, your Number for 

 -*■■*■ August last has only just come to hand, which will ac- 

 count for the delay of my present notice of one of Mr. H. F. 

 Talbot's proposed experiments. My object in sending the 

 following remarks is for the purpose of inducing any person 

 who may be inclined to try his second experiment, to pause 

 before they commence such a trial as he proposes. 1 admit, 

 with Mr. Talbot, that it would be very desirable, if possible, 

 to reduce the problem respecting the greatest depth of the 

 ocean to the test of actual experiment; but I must most de- 

 cidedly object to his proposed method. The prima facie part 

 of his principle is, that there must be ground, (a point that is not 

 admitted by every one,) or his shell will never explode: but 

 without mooting this point, if there is any credit to be placed 

 on Mr. Perkins's experiments, (and I believe no one doubts 

 them,) Mr. Talbot's shell xvox\\(\f oat long before it could reach 

 the bottom, as it is now pretty well ascertained that at a cer- 

 tain depth the sea is specifically heavier than any body which 

 we are acquainted with, consequently a cast-iron shell could 

 not penetrate it. 



As to the danger of the experiment, there could be none ; 

 for supposing it did reach the bottom and exploded, it should 

 be borne in mind that miners and others who have occasion 

 to blast rocks under water, find that about 3 or 4 fathoms is 

 quite sufficient to protect them from any injury. 



Again, supposing that the experiment could be tried as Mr. 

 Talbot proposes, it seems to have escaped his recollection 

 that no body, in a moving current of water, can fall perpendi- 

 cularly ; and also that at certain depths there are various cur- 

 rents running, all which would tend to give erroneous results. 



