98 On Massey'i Sounding Machine. 



made in the bottom of the air tube, which restored the 

 equilibrium between tlie interior and the exterior. But 

 thus perforated, the rotary motion was true only in as 

 much as the descent was not less than 17 fathoms per 

 minute. To obviate this objection the hole was suppressed, 

 and brass disks were introduced into the interior of the 

 tube as a support, and they have rendered it proof against 

 any pressure to which the machine has hitherto been ex- 

 posed, as will be seen by the extracts from the following 

 letters. 



1 . From Mr. Thomas Stokes, master of the fleet off 

 Cadiz, May 31, 1810. He savs, " I have had the oppor- 

 tunity of trying one of the rotators in a calm, and sunk it 

 180 fathoms, and it came up as perfect as when it was put 

 in the water. I therefore ctmoratulate you on having got 

 over the only objection that seems at present to be against 

 the sounding machine." 



2. From Mr. Alexander Lumsdale, master of the Cale- 

 donia, 120 guns, September 7, 1810, who writes: "The 

 late improvement you have made in the rotator, has made 

 it a very complete thing. I have tried it in nearly 200 fa- 

 thoms without its receiving the least injury, and am of 

 opinion the great utility of the sounding machine only re- 

 quires to be generally known, to make it more sought 

 after." 



3. From Mr. John Tapper, master of the Clyde, July 

 S2, 1810, who says: " I have to acquaint vou that F made 

 frequent trials of your improved roiator in 200 fathoms 

 with a lead of 14lbs. attached to the proper lead* issued 

 from the dock-yard in the maimer Mr. Stokes requested, 

 and found it equal to the pressure of the water u ith the 

 above-mentioned depth and weight. It came up in perfect 

 good state, not a drop of water had penetrated through it. 

 My opinion is that no alteration is necessary." 



He then proceeds on a suliject that has not been men- 

 tioned in this Report, that is to say, Survsyuig, and he con- 

 tinues thus : " The machine is altogether an excellent in- 

 vention, and I found it of very great use to me in sounding 

 the river Tagus, where the water is deep, from 20 to 30 

 fathoms. Jn a boat with sails set. f could get true sound- 

 ings in sailing to and fro, hit wilh the common lead, I 

 should have been obliged to lower the sails, so as for the 



* It has been found mi«re advantagto'.is to fix the additional lead at 30 

 o'r 40 fathoms oh>i:e Ihe machine, by which means the buoyancy of the line 

 is compensated, with les$ danger of the line breaking wKeu the machine 

 ie hauled in. 



boat's 



