Also 8 caissoon. [a. F. caisson large chest, f. caisse chest.]
1. Mil. a. A chest containing bombs or other explosives, to be buried and fired as a mine.
1704. in J. Harris, Lex. Techn.
1721. Bailey, Caisson [in Fortification], a Chest of Wood holding four or 6 Bombs, or sometimes filled only with Powder, and buried under Ground, by the Besieged, to blow up a Work the Besiegers are like to be Masters of.
1755. Johnson, Caisson, a chest of bombs or powder, laid in the enemy’s way to be fired at their approach.
1772. Simes, Mil. Guide, s.v.
b. A chest containing ammunition; a wagon for conveying ammunition. Also fig.
1704. in J. Harris, Lex. Techn.
1708. Kersey, Caisson, a covered Waggon, or Carriage for Provisions, or Ammunition for an Army.
1730–6. in Bailey.
1812. Examiner, 23 Aug., 532/1. The fruits of the three actions of Ostrovno are ten pieces of cannon of Russian manufacture taken, the cannonneers sabred; 20 caissons of ammunition; [etc.].
1865. Bushnell, Vicar. Sacr., III. iii. (1866), 285. The retributive causes of nature roll out their heavy caisson with us.
1870. Echo, 14 Nov. Several artillery caissons captured at Orleans were found to be filled with wearing apparel.
2. Hydraulics.
a. A large water-tight case or chest used in laying foundations of bridges, etc., in deep water.
1753. Chambers, Cycl. Supp., Caisson is also used for a kind of chest used in laying the foundations of the piers of bridges.
1765. Ann. Reg., 12/2. The greatest part of the first course [of the sixth pier of Blackfriars bridge] carried by the Caissoon.
1823. P. Nicholson, Pract. Build., 305. M. Labelye erected the piers [of Westminster Bridge] in caissons, or water-tight boxes.
1875. B. Richardson, Dis. Mod. Life, 70. The effect of atmospheric pressure on men who are employed to work in caissons.
b. In Canal-making. Formerly, a large water-tight cistern or reservoir made at any point where the canal had to be extended over lower ground, in order to enable the boats to come forward with material for the embankment.
1769. De Foe’s Tour Gt. Brit., III. 272. At Stretford, three Miles off, is the Caisson 40 Yards long by 32.
1838. Southey, Lett. (1856), IV. 546.
1861. Smiles, Lives Eng., I. 382. Brindley … had the stuff required to make up the embankment brought in boats … conducted from the canal along which they had come into caissons or cisterns placed at the point over which the earth and clay had to be deposited.
c. A vessel in the form of a boat used as a floodgate in docks.
1854. Fairbairn, in Proc. Inst. C. Engin., 9 May. The employment of caissons for closing the entrance to wet or dry docks.
1867. Smyth, Sailor’s Word-bk., Caisson, a vessel fitted with valves, to act instead of gates for a dry dock.
d. ‘A sort of float sunk to a required depth by letting water into it, when it is hauled under the ship’s bottom,… and on pumping out the water floats her’ (Smyth, Sailor’s Word-bk.); = CAMEL.
1811. Naval Chron., XXV. 219. This caisson or floating dock is made of wrought iron.
3. Arch. ‘A sunken panel in ceilings, vaults, and cupolas.’ Gwilt, Encycl. Archit.
4. attrib. and in comb., as caisson disease (see quots.); caisson-gate = sense 2 c.
1866. Cornh. Mag., March, 381. 23 feet depth of water when the caisson-gates are opened.
1883. W. C. Conant, in Harper’s Mag., July, 945/1, note. The ‘caisson disease’ is the result of living under atmospheric pressure greatly above that to which the human system is normally adapted.
1887. Health, 11 March, 394. What is known as the ‘caisson disease’ is not produced by the mere increase of atmospheric pressure, but by the sudden diminution of it on leaving the caisson, which produces ruptures of small blood-vessels.
