“Fida silentia sacris.”

Fauere sacris, fauere linguis, and {41}_pascere linguam_, were forms of speech appropriated to their sacred rites, by which they enjoined silence, that the act of worship might not be disturbed by the slightest noise or murmur.  Hence also they honoured Harpocrates as the god of silence; and Numa instituted the worship of a goddess under the name of Tacita.

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SPIRIT OF DISCOVERY

FILTERING APPARATUS.

(To the Editor of the Mirror.)

[Illustration: 
A A. The Pot. 
B B. The Triangular Board. 
C. The Cover. 
D. Vessel to receive the Filtered Water. 
E. Dotted Line, showing the Proportion of
     Charcoal and Sand.]

Herewith I send you an outline drawing of an economical filtering apparatus, suitable for the use of any dwelling.  Its construction is perfectly simple, and at the cost of a few shillings in its erection.  The pot consists of an unglazed inverted vessel, manufactured at potteries for the use of sugar-bakers, and placed through a hole in a triangular board, resting upon two ledges, occupying a corner in a kitchen or any other apartment.  In the inside of the pot a bushel of the whitest sand is to be introduced; which sand, after being washed in a clean tub with about three changes of water, to dissolve and clear away the clayey matter, is to be mixed with half a peck of finely-bruised charcoal.  This will fill about one-third of the pot; but before the sand is placed in the vessel, the small hole at the bottom of the pot should have an oyster-shell placed over it, with the convex side uppermost, to prevent the sand washing through.  This filters foul water perfectly pellucid and clear very quickly, as I have seen its effects for years with the most perfect success.  When the sand becomes foul by time, it can be taken out and washed, or fresh materials can be repeated; great care should be observed not to put more water in the pot than your vessel underneath will receive.

JNO.  FIELD.

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Effects of Lightning.

The analogy between the electric spark, and more especially of the explosive discharge of the Leyden jar, with atmospheric lightning and thunder, is too obvious to have escaped notice, even in the early periods of electrical research.  It had been observed by Dr. Wall and by Gray, and still more pointedly remarked by the Abbe Nollet.  Dr. Franklin was so impressed with the many points of resemblance between lightning and electricity, that he was convinced of their identity, and determined to ascertain by direct experiment the truth of his bold conjecture.  A spire which was erecting at Philadelphia he conceived might assist him in this inquiry; but, while waiting for its completion, the sight of a boy’s kite, which had been raised