CHAULNES (The Duke De)

, a peer of France, but more honourable and remarkable as an astronomer and mathematician. He was born at Paris Dec. 30, 1714. He soon discovered a singular taste and genius for the sciences; and in the tumults of armies and camps, he cultivated mathematics, astronomy, mechanics, &c. He was named honorary-academician the 27th of February 1743, and few members were more punctual in attending the meetings of that body; where he often brought different constructions and corrections of instruments of astronomy, of dioptrics, and achromatic telescopes. These researches were followed with a new parallactic machine, more solid and convenient than those that were in use; as also with many reflections on the manner of applying the micrometer to those telescopes, and of measuring exactly the value of the parts of that instrument. The duke of Chaulnes proposed many other works of the same kind, when death surprised him the 23d Sept. 1769.

He had several papers published in the volumes of Memoirs of the Academy of Sciences, as follow:

1. Observations on some Experiments in the 4th part of the 2d book of Newton's Optics: an. 1755.

2. Observations on the Platform for dividing mathematical instruments: 1765.

3. Determination of the distance of Arcturus from the Sun's limb, at the summer solstice: 1765.

4. On some means of perfecting astronomical instruments: 1765.

5. O some experiments relative to dioptrics: 1767.

6. The art of dividing mathematical instruments: 1768.

7. Observations of the Transit of Venus, June 3, 1769: 1769.

8. New method of dividing mathematical and astronomical instruments. |

CHAUSE TRAPPES, or Caltrops, or Crowsfeet, are iron instruments of spikes about 4 inches long, made like a star, in such a manner that whichever way they fall, one point stands always upwards, like a nail. They are usually thrown and scattered into moats and breaches, to gall the horses feet, and stop the hasty approach of the enemy.