Category: Science - Physics
A. The rays of the sun, collected by the Burning Glass, are all _bent to one point_, called the "focus;" thus the heat and light, (which should be diffused over the _whole_ glass,) being gathered together into one point, are very greatly increased.
A. The rays of the sun, collected by the Burning Glass, are all _bent to one point_, called the "focus;" thus the heat and light, (which should be diffused over the _whole_ glas...
5. CHAPTER II.A. Yes; they often run a considerable way along the ground, then _stop_ for a little time, and _burst in numberless pieces_: sometimes _each of these pieces_ will explode; and a...
6. CHAPTER III.A. Many things, when their chemical constitution is changed, (either by the abstraction of some of their gases, or by the combination of others not before united,) evolve _heat_...
7. CHAPTER IV.A. When the hot air of the chimney has been cooled by the _external_ air, it can no longer _buoy up_ the solid smoke; so it falls to the earth in condensed flakes, called "blacks."
8. CHAPTER V.A. 1st--When the _hydrogen_ of the tallow and _oxygen_ of the air _condense into water_, a _vacuum_ is made; and the air is disturbed, as a _pond_ would be, if a pail of _water_...
9. CHAPTER VI.A. Yes. Whenever blood _flows from a wound_, some _vein_ must be divided; and as you cannot insert a needle into _any part of the body without bringing blood_, therefore these l...
10. CHAPTER VII.A. They used to place a soft iron nail upon their anvil; strike it two or three times with a hammer; and the point became _sufficiently hot to light a brimstone match_.
11. CHAPTER VIII.A. They take a piece of dry wood (sharpened to a point), which they rub quickly up and down a _flat piece_, till a _groove_ is made; and the _saw-dust_ (collected in this groove...
12. CHAPTER IX.A. Chestnuts contain a great deal of air, which is expanded by the heat of the fire; and, as the thick rind prevents the air from escaping, it violently _bursts through, slittin...
13. CHAPTER X.A. The iron stove _contracts again_, as soon as the fire is removed; and (as it shrinks into a smaller space) the parts _rub against each other again_, and the _bricks are again...
14. CHAPTER XI.A. When the _surface of the earth_ is _warmer than the air_, the vapour of the earth (being condensed by the chill air) becomes _mist or fog_. But when the _air_ is _warmer than...
15. CHAPTER XII.A. The air contains heat, and changes the _surface of the water into vapour_; this vapour (blending with the air) _is soon wafted away_; while _fresh_ portions of air _blow over...
16. CHAPTER XIII.A. _Wood is a bad conductor of heat_; and, therefore, heat does not traverse freely through it: hence, though one end of a stick be blazing-hot, the other end may be quite cold.
17. CHAPTER XIV.A. _Black cloth absorbs_, but does not _conduct heat_: thus, if black cloth be laid in the sun, _it will absorb the rays_ very rapidly; but if _one end of the black cloth_ be ma...
18. CHAPTER XV.A. If a piece of tin were thrust _into_ a fire, it would be _in actual contact with the fire_; but if it be _held before a fire_, the heat of the fire _falls upon it in rays_.
19. CHAPTER XVI.A. Yes; when the tea-pot is _set on the hob "to draw,"_ the black _earth_ is the _best_, because it _absorbs heat_: but when the tea-pot is _not_ set on the hob, the bright _met...
20. CHAPTER XVII.A. The water _nearest the fire is first heated_, and (being heated) _rises to the top;_ other cold water succeeds, is _also_ heated, and rises in turn; and this interchange keep...
21. CHAPTER XVIII.A. The blood derives its redness from the _oxygen_ of the air inhaled; but, as the air in close rooms and cities _is not fresh_, it is _deficient in oxygen_, and cannot turn the...
22. CHAPTER XIX.A. If a pit or well contain carbonic acid, _a candle_ (let down into it) _will be instantly extinguished_. The rule, therefore, is this--Where a _candle will burn, a man can liv...
23. CHAPTER XX.A. Because the metal wire is a very _rapid conductor of heat_; and when the flame of burning gas in the lamp reaches the wire gauze, the heat (which is needful to produce flame)...
24. CHAPTER XXI.A. Perhaps _all_ the ghost stories (which deserve any credit at all) have arisen from the ignited gas of church-yards lurking about the tombs, to which _fear_ has added its own...
25. CHAPTER XXII.A. If a bladder _half full of air_ (tied tight round the neck), were laid before a _fire_, the heat of the fire would expand the air so much, that the bladder would soon be _ent...
26. CHAPTER XXIII.A. Because the mercury in the tube _rises and falls_, as the air becomes lighter or heavier: and we can generally tell by the _weight_ of the air, what kind of weather to expect.
27. CHAPTER XXIV.A few years ago, some fishermen (who wintered at Nova-Zembla), after they had been shut up in a hut for several days, _opened the window_, and the cold external air rushing in,...
28. CHAPTER XXV.29. CHAPTER XXVI.Q. _In winter time, FOOT-MARKS and WHEEL-RUTS are often covered with an icy NET-WORK, through the interstices of which the soil is clearly seen,--WHY does the water freeze in NE...
30. CHAPTER XXVII.A. Because the pupil (which _contracted_ in the bright room) does not _dilate instantaneously_; and the contracted pupil is not able to _collect rays enough_ (from the dark road...
31. CHAPTER XXVIII.A. The _keys of the piano_ (being struck with the finger) lift up a little hammer which _knocks against a string_; and the vibration thus produced, sets in motion the sound-wave...
32. CHAPTER XXIX.A. Because the water in the saucer is _supped up_ by the mould (through the hole at the bottom of the flower-pot), and is transferred to the stem and leaves of the plant by CAPI...