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Wedge, a triangular piece of wood or metal, to cleave

stone, &c. Its principle explained, I. 145. Its advantages in cleaving wood, I. 146. What instru

ments referred to, I. 147. Well, how to find the depth of one, I. 58. Wheel and axes described, I. 126. For what purposes

used, ib. Its power estimated, I. 127. How increased, I. 128. Explained on the principle of the

lever, I. 131. White, Mr. James, his invention of a crane, I. 130.

His patent pulley, 1. 137. Wind, what it is, 11. 312. The cause of, II. 313.

Experiment on, II. 314 and 319. Definition of, II. 315. Its direction denominated, ib. The cause of its variableness in England, II. 320. How to find

its velocity, II. 322. Table of, II. 324... Winds, how many kinds, and why so named, I.

315. Winter, why colder than the summer, I. 247.

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Year, its length, how measured, 1. 265. Gregorian, what meant by, I. 268. The beginning of, changed from the 25th of March to the 1st of January, 1. 269.

Zenith, that point of the heavens over one's head.
Zinc, experiment with, III. 350.
Zodiac, a belt in the heavens, sixteen degrees broad,

through which the ecliptic runs. Signs of, I. 186. Dr. Watts's lines on, I. 189.

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