138 POPULAR LECTURES AND ADDRESSES. 



of a mile off, and before a boat can be manned 

 and cast off from her, she must be at least half 

 a mile from the life-buoy with its living burden. 

 But look at the light the more the water washes 

 over it, the more brightly it burns. It will burn 

 for three-quarters of an hour, and can be seen 

 at a distance of five or six miles. It disappears 

 for a few seconds perhaps behind a wave, or 

 for the want of continuity which you see in the 

 flame, and then you see it blaze up again with 

 increased brilliance, and so on for three-quarters of 

 an hour. It goes on disappearing and blazing 

 up again visibly out of the horizon when at least 

 five or six miles off, as I have myself seen in the 

 river Para. The boat, now manned and rowing 

 away from the ship, has no difficulty in knowing 

 where to steer for. Guided by the light, they 

 will pull away through a heavy sea, and in 

 a quarter of an hour they have their comrade 

 in the boat with them. By this time the ship, 

 also guided by the light, has steamed or sailed 

 close up to them, and in a few minutes they 

 are all on board. 



