\q6 philosophical transactions. [anno 1751. 



deck, he took out the clapper, and having suspended it also by thread, which, 

 with its own length, made 4<1 inches; the angle, which the rim of the bell made, 

 with a line let fall perpendicular from the pin, on which the clapper hung, was 

 equal to 34'. He then held the clapjjer at the same angle, on the other side 

 of the line, in order that the strokes at different times might be with the same 

 force; when, letting it go, it struck the bell. In its return he catched it, and 

 counting the vibrations, he heard them distinctly only 3 times; whereas, when 

 the hold was well ventilated, it vibrated 5 times; but its vibrations were not so 

 quick in the latter as in the former case. 



The ship's crew was very healthy, though their number was 130, not one 

 being sick aboard. The hold, which in most ships is very moist, in theirs was 

 quite dry. Their cargo arms, kept there in upright chests, without wrappers, 

 came out as bright as from a recent polish. The ventilator was far from being 

 inconvenient aboard of them, on the contrary, it was good exercise for the slaves, 

 and a means of preserving the cargo and lives. On the passage, Capt. E. made 

 several trials with the bucket sea-gage, in latitude 25' 13" north, longitude 25' 

 12" west. He let it down to different depths, from 36o feet to 5346 feet; when 

 he discovered, by a small thermometer of Fahrenheit's, made by Mr. Bird, 

 which went down in it, that the cold increased regularly, in proportion to the 

 depths, till it descended to 39OO feet: whence the mercury in the thermometer 

 came up at 53 degrees; and though he afterwards sunk it to the depth of 5346 

 feet, that is, a mile and 66 feet, it came up no lower. The warmth of the water 

 on the surface, and that of the air, was at that time by the thermometer 84 

 degrees. The water might be a degree or two colder when it entered the bucket, 

 at the greatest depth, but in coming up had acquired some warmth; for he found 

 that the water which came up in the bucket, having stood 43 minutes in the 

 air, the time of winding it up, the mercury rose above 5 degrees. When the air 

 had rendered it equally warm with the water on the surface, he tried their weight, 

 by weighing equal quantities very exactly, as also by the hydrometer, and found 

 that from great depths the heaviest, and consequently the saltest water. 



This experiment, which seemed at first but mere food for curiosity, became 

 very useful to them. By its means they supplied their cold bath, and cooled 

 their wines or water at pleasure; which was vastly agreeable in that burning 

 climate. 



On the preceding account Dr. Hales remarks that the bucket sea-gage, above- 

 mentioned, and which he provided for the Captain to find the different degrees 

 of coolness and saltness of the sea, at different depths, was a common houshold 

 pail or bucket, with 2 heads in it : which heads had each a round hole in the 

 middle, near 4 inches diameter, covered with valves which opened upwards ; 

 and that they might both open and shut together, there was a small iron rod 



