182 Scientific Intelligence. 



ful to small ships, which, deceived by the appearance of fine weather, ven- 

 ture into the ocean, and expose themselves to dangers of which they often 

 become the victim.' See Zachs' Corresp. Astron. vol. xii. p. 137. 



29. Mr Jones's Improved Hygrometer. This instrument, an account 

 of which was read at the Royal Society, has for its object to ascertain the 

 temperature at which dew is deposited from the atmosphere. It therefore 

 differs from Mr Daniell's only in having the frigorific action applied im- 

 mediately to the tube of the thermometer which is used to measure the 

 temperature. The tube is large and cylindrical, slightly flattened, and ex- 

 tended at the end. This end of the tube is turned upwards, the stem of 

 the thermometer being twice bent at right angles. This end is made of 

 black glass and exposed, but the rest of the tube is covered with muslin, 

 which, being moistened with ether, the mercury is cooled, and dew at length 

 settles on the exposed part, at which instant the degree indicated in the 

 scale is read off. See p. 127 of this Number. 



30. Remarkable Waterspout. This extraordinary phenomenon was seen 

 on the 6th July 1822, in the plain of Arson val, a village about six leagues 

 \V. S. W. of St Omer, and six from Boulogne. About l h 35' P. M. clouds 

 coming from different parts collected rapidly, and formed a single one 

 which covered the whole horizon. From these clouds a thick vapour im- 

 mediately descended in the shape of an inverted cone, and having the 

 bluish colour of burning sulphur. The apex of the cone next the earth 

 revolved with great velocity, and formed an oblong mass, of about thirty 

 feet detached from the cloud. It rose with a noise like the bursting of a 

 large bomb, leaving a hollow in the ground, of from ^0 to 25 feet cir- 

 cumference, and from 3 to 4 feet deep in the middle. It then set off in the 

 direction of W. to E. knocked down a barn, and gave to the neighbouring 

 farm-house a shock like that of an earthquake. It overthrew from 25 to 

 30 trees, and laid them in such a variety of directions, as to prove that it 

 advanced with a rotatory motion. It next travelled through a distance of 

 two leagues without touching the ground, carrying off huge branches of 

 trees which it threw out with great noise to the right and left. Having 

 reached the highest point of the wood Fauquembergue, it carried off the 

 tops of several oaks, which it took along with it, below the village of Ven- 

 dome, at the foot of the hill on the east of the forest. In that commune 

 it did no other harm than to carry off a very large sycamore tree, root and 

 branch, to a distance of 600 paces. 



Continuing its route like a ball fired en ricochet, it attacked the village of 

 Audinctun, where it demolished the roofs of three houses, and carried away 

 several trees, among which were five ashes of great height. After quitting 

 the valley, at the mouth of which these two villages are situated, it ascended 

 the mountain de Capelle, and several ploughmen saved themselves by lying 

 down and holding firmly by their ploughs, one of which was driven so 

 deep into the ground, that three horses were unable to pull it out. M. 

 Demarquoy, who has described this phenomenon minutely, observes that 



