tions, I. 328, 329. Its satellites and rings, I. 330,
331. The length of its day and night, I. 331.
Screw, an inclined plane wrapt round a cylinder. Its
principle explained, I. 149. Of what composed, I.
150. Examples of, I. 151. Used by paper-makers,
1. 155. Its power estimated, ib.
Season, the hottest, I. 248.
Seasons, variety of, on what depends, I. 238, and 244.
different, how accounted for, I. 232, and 238–254.
How produced, I. 248.
Ship, damaged by lightning, III. 312.
Silurus electricus, described, III. 335.
Silver, experiment with, III. 349.
Slaves, how they get at their master's rum, II. 140.
Smoke, the reason of its ascent. II. 265.
Smoke-Fack, its principle, II. 314.
Solar system, described, I. 197-205.
Selder, for what used, I. 34.
Sound, conductors of, II. 275, 276.
be heard, II. 281. How fast it travels, II. 283.
Velocity of, applied to practical purposes, II. 285
-287.
Spark, electrical, its nature, III. 287.
Specific gravity, what meant by, II. 36.
plained and illustrated, II. 92-137.
II 95.
Galvanic, its
Of bodies ex-
How to find,
Spectacles, their construction, uses, and different
kinds, III. 128-130.
Spirit, rectified, what meant by, II. 144, &c.
Springs, intermitting, explained, II. 163.
St. Paul's, whispering gallery of, principle explained,
II. 306.
Stars, how to find the names of, I. 173-177. Why
marked on the globe with Greek characters, I.
177. Fixed, their apparent motion, I. 229. Why
not seen in the day, I. 231. Fixed, their number,
I. 161-163. May be distinguished, I. 169. Fixed,
their immense distance, I. 258. Fixed, description
of, I. 345–349. Their uses, I. 350. Falling, what
they are, III. 310.
Steam-engine, its use, II. 325.
When invented, II.
327. Its structure, II. 330. The application, II.
341, 342. That of Messrs. Whitbread described,
II. 344. Its power calculated, ib.
Steelyard, a sort of lever, I. 112. Its advantages over
a pair of scales, I. 113.
Storms, by what occasioned, II. 321.
Suction, no such principle in nature, II. 224-230.
Sulphuret, alkaline, what, III. 365.
Summers, two in a year, in some places, I. 252.
Sun and clocks, seldom together, I. 193.
Sun, declination of, I. 190. Longitude of, I. 195.
Has not latitude, I. 195. Its magnitude, 1. 198.
Why it appears so small, ib. Its distance from
the earth, I. 199. Annual motion of, how observ
ed, I. 233. Reasons for, I. 180. Nearer to the
earth, in winter, than in summer, I. 246. A de-
scription of, I. 342-344.
Swimming, theory of, II. 149. How to be attained,
II. 150. Less natural to man than to other land
animals, II. 150.
Syphon, the structure of, explained, II. 156. Its prin
ciple, II, 158.
Syringe, its structure explained, II. 219. Condensing
one described, II. 260.
Tables, Galvanic, III. 365, 366.
Tangent, a straight line touching the circumference
of a circle in one point.
Tangible, capable of being felt or handled.
Tantalus's cup, II. 160.
Taste, a disagreeable one, excited by the union of
metal's placed on and under the tongue, III. 350.
How accounted for, III. 351.
Telescope, refracting, explained, III. 143.
151. Reflecting, explained, III. 153.
schel's, III. 157.
Terms, technical, derived from the Greek language,
.II. 11.
Thermometer, its construction and uses, II. 369–375.
Its scale, II. 375. Wedgewood's, II. 378. Reau-
mur's scale compared with Fahrenheit's, II. 382.
Heat, scale of, II. 381.
Thunder, how produced, II. 278.
Tides, the causes of, explained, I. 289–296. Two
every 25 hours, I. 293. Different in different
places, I. 294. When the highest happen, I. 296,
Time, equal and apparent, how distinguished, I. 255,
256. On what the difference depends, I. 256.
Equation of, I. 193 and 255-264. Division of,
I. 271.
Time and space, clear ideas of, necessary to be form-
ed, I. 103.
Torpedo, described, III. 330.
Torricellian experiment, II. 161.
Transferrer, an instrument used in pneumatics.
Transit of Venus, her passages over the sun's face.
Trembling-eel, noticed, III. 335.
Triangle, what meant by, I. 17. Any two sides of,
greater than the third, I. 94.
Tropics, circles parallel to the equator.
Trumpet, speaking, described, II. 288-293. When
first used, II. 291.
Trumpets, for deaf persons, II. 292.
Twilight, the degree of light experienced between
sun setting or rising and dark night.
Undulation, swinging or vibrating.
Vacuum, a place void of air.
Valve, a sort of trap door.
Valves, what meant by, II. 180.
Vegetables, how blanched, III. 79.
Velocity, a term applied to motion. Accelerating what
meant by, I. 56.
Venus, the planet, its distance from the sun; the velo-
city of its motion; its magnitude, I. 312-315.
Why an evening and why a morning star, I. 315.
Transit of, what meant by, I. 316.
Vernier, its construction and use, II, 356.
Vertex, the top of any thing.
Vibration, the swinging motion of a pendulum.
Vision, the manner of, III. 120.
Volatile, any light substance that easily evaporates,
Voltaic batteries, III. 356–358. Shock, III. 357-
359.
Voltaism, III. 356,1&c.
Wall, leaning one, at Bridgnorth, I. 68.
Water, pure rain, the standard to compare other bo-
dies with, II. 97. Weighs the same every where.
ib. Always deeper than it appear to be, II. 153
and IH. 36. How raised from deep wells, II. 191
-193. Formed of two gasses, III. 351. Decom-
posed, III. 367.
Water-spouts, their cause, III. 318. How dispersed,
Weather, rules for judging of, II. 399–401.
Wedge, a triangular piece of wood or metal, to cleave
stone, &c. Its principle explained, I. 145. Its ad-
vantages 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 in-
creased, I. 128. Explained on the principle of the
lever, I. 131.
White, Mr. James, his invention of a crane, I. 130.
His patent pulley, I. 137.
Wind, what it is, II. 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, II.
315.
Winter, why colder than the summer, I. 247.
Year, its length, how measured, I. 265. Gregorian,
what meant by, I. 268. The beginning of, changed
from the 25th of March to the 1st of January,
I. 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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