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HYDROSTATICS AND PNEUMATICS.

(Cabinet Cyclopaedia, vol. xvii.)

Easier to swim in the Sea than in a River.

Sea water has a greater buoyancy than fresh water, being relatively heavier; and hence it is commonly said to be much easier to swim in the sea than in a river:  this effect, however, appears to be greatly exaggerated.  A cubic foot of freshwater weighs about 1,000 ounces; and the same bulk of sea water weighs 1,028 ounces; the weight, therefore, of the latter exceeds the former by only 28 parts in 1,000.  The force exerted by sea water to support the body exceeds that exerted by fresh water by about one thirty-sixth part of the whole force of the latter.—­By Dr. Lardner.

Ice lighter than Water.

It is known that in the process of congelation, water undergoes a considerable increase of bulk; thus a quantity of water, which at the temperature of 40 deg. measures a cubic inch, will have a greater magnitude when it assumes the form of ice at the temperature of 32 deg.  Consequently ice is, bulk for bulk, lighter than water.  Hence it is that ice is always observed to collect and float at the surface.—­A remarkable effect produced by the buoyancy of ice in water is observable in some of the great rivers in America.  Ice collects round stones at the bottom of the river, and it is sometimes formed in such a quantity that the upward pressure by its buoyancy exceeds the weight of the stone round which it is collected—­consequently it raises the stone to the surface.  Large masses of stone are thus observed floating down the river at considerable distances from the places of their formation.—­Ibid.

Domestic Use of the Hydrometer.

The adulteration of milk by water may always be detected by the hydrometer, and in this respect it may be a useful appendage to household utensils.  Pure milk has a greater specific gravity than water, being 103, that of water being 100.  A very small proportion of water mixed with milk will produce a liquid specifically lighter than water.—­Although the hydrometer is seldom applied to domestic uses, yet it might be used for many ordinary purposes which could scarcely be attained by any other means.  The slightest adulteration of spirits, or any other liquid of known quality, may be instantly detected by it; and it is recommended by its cheapness, the great facility of its manipulation, and the simplicity of its results.—­Ibid.

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THE GATHERER.

  A snapper up of unconsidered trifles. 
  SHAKSPEARE.

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The late Lord Clonmel, who never thought of demanding more than a shilling for an affidavit, used to be well satisfied provided it was a good one.  In his time the Birmingham shillings were current, and he used the following extraordinary precaution to avoid being imposed upon by taking a bad one:—­“You shall true answer make to such questions as shall be demanded of you touching this affidavit, so help you God.  Is this a good shilling?”