Eugene Fairfield MacPike (ed.), History of Science Society Publications: New Series, Vol. 2: Correspondence and Papers of Edmond Halley
13. A Relation of the Diving Bell.
Having received the Societys commands to give them an account in writing of the success of my attempt on the Guiney frigat, and of the improvemts I have made of the Diving Bell. be pleasd to take the following relation.
The Diving tub was made 5 foot at Bottom where it was open 3 foot at top and 5 foot deep which contained about 64 foot in capacity and consequently required about 36 hundred weight to sink it which I applied as near as I could to make it tractable partly by bestowing about 10 hund. of Lead on the outside therof which pg 151besides the weight had the use of of making it perfectly tight, for the rest of the weights I hung them on two strong Iron rings which were one over the other as near the bottom as cold be with convenience, and under the bell by three ropes I fastned a stage about 2 foot below to stand on, which 3 ropes held likewise each 2 ct. weight which contributed greatly to keeping the whole engine upright and secure from tripping: Within the bell I placed a bench about a foot from the bottom for the men below to sitt on when they should be cold and wheron a man might sett with all his clouths at any depth drie. I made likewise in the top of the bell a window to let in the light, which was very thick and strong but as clear glass as could be gotten and I placed a small Cock in the same crown of the bell to let out the hott and effete air unfitt for farther respiration:
When we lett down this engine into the sea we all of us found at first a forceable and painful pressure upon our Ears which grew worse and worse till something in the ear gave way to the Air to enter, which gave present ease, and at lenght we found that Oyle of Sweet Almonds in the Ears, facilitated much this admittance of the Air and took of the aforesd pain almost wholly.
Then it was observable that the water entered very deep into the bell, if we lowerd much at a time, and that at two fath. depth we had a foot water in it, or up to our bench, wherfore we were obliged to lower not above 2 fath. or 15 foot at first at a time and so drive out the water that entred before we lowerd any more, wherin consisted the principall invention I can bost of.
To do this I took a good Iron bound cask which held about 40 gall. and coated it over with lead so that it would sink empty and in this I made a bung hole in the parts designed to sink undermost, and a cock in that to be uppermost: this I contrived two guies for which when it sunk conveied it alwais under the Diving Bell, when turning the Cock the air rushed out with great force into the bell whilest the water entred by the bunghole in the bottom of the Cask, then when the Air was all gone and the Cask ceasd to blow, by a signall given the cask was hald up again and being above water all the water run out at the bunghole and the Air entred by the Cock, which being turned the Cask was again sent down as before. Thee cask would usually drive out all the water that entred in lowering 2 fathoms when we were down as low as we intended then we began to let out our hot Air at the top of the bell just before wee received a Cask of fresh, wherby we renewed and recruted what was rendred effete and unfitt for respiration.
By this means I have kept 3 men 1 under the water and in ten pg 152fathoms deep without any the least inconvenience and in as perfect freedom to act as if they had been above. It was observable that when we were ha'ld up, the Air coming to be rarified would immediatly fill with a white fogg as thick as any winter fog appears, which likewise would stink like our foggs here, but which would vanish upon the bells coming above water in an instant as it arose.
We observed that we had 2 sorts of light, the one that came by reflection from the water under the bell which cast a pale sea green colour on all objects it was cast on, and that by refraction from above by the glass which cast a pale Cherry colour or flesh colour especially when the sun shone strong: we found likewise that a man that hurt himself by bruising his finger had his blood tinged of a deep Verdigrese green, without any sign of red in it, and it was to be noted that he bled in so great quantity whilest he was under water as if a mans nose had bled violently, which was without doubt occasiond by the great pressure of the Air we were then under.
This method of keeping men under water has no limits, for if the bell be made greater and the Air Cask proportionable any number of men assigned may be suppleyd with breath for as long time and at as great a depth as shall be desired and by what we have found at 10 fathom I see no reason to doubt but a man may be well enough in 20 or 30 fathoms without harm
[Read Sept. 23, 1691.]