386 POPULAR LECTURES- AND ADDRESSES. 



depths found in each, case except the cast at 9 A.M. 

 on the 6th, and all but one of the last ten casts. 



It is a pleasure to me to be able to add, that the 

 sounding machine has also been successfully used 

 in the Royal Navy. Admiral Beauchamp Sey- 

 mour and Captain Lord Walter Kerr having kindly 

 taken it on board H.M.S. Minotaur for trial last 

 summer, Lord Walter Kerr, on his return from 

 Vigo, wrote regarding it as follows : 



" The sounding machine is most serviceable, 

 We have been using it constantly when running 

 up Channel, from the time of crossing the line of 

 soundings to the time of reaching Plymouth ; and, 

 though running before a gale of wind, with a heavy 

 sea, at the rate of ten knots, we were able to get 

 soundings as if the ship had been at anchor. We 

 were able to signal to the squadron each sounding 

 as it was obtained ; thus, in thick weather, verifying 

 our position by soundings without having to round 

 the ships to." 



\Extract from Printed Instructions for the Use of Sir 

 William Thomson's Navigational Sounding Machine^ 



Regular Use of the Machine. WlIEN NAVIGAT- 

 ING OUT OF SIGHT OF LAND IN LESS THAN IOO 

 FATHOMS, IF THERE IS ANY DOUBT AS TO THE 

 SHIP'S POSITION, WHETHER FROM THE SKY NOT 

 BEING CLEAR ENOUGH FOR SIGHTS OR FROM THE 

 ERRORS OF THE. CHRONOMETERS NOT BEING 



