Page:Popular Science Monthly Volume 37.djvu/561

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4. The Earth Connection.—It is not easy in all cases to insure that this is satisfactory. Electricity will not pass at all so easily into dry earth as into wet earth, and merely plunging the end of the rope or tape into wet earth is not sufficient. The conductor from the building should be soldered at its end to a large sheet of copper, say at least two square yards in area, buried in damp soil, or else soldered to the water or gas mains, so as to insure that a large surface of metal is in contact with damp earth.

Supposing that the whole system of protection against damage from lightning has been properly planned, the work should be carefully tested after its completion, because injury to it often occurs at the very last, owing to accidental causes, or to the carelessness of workmen. Conductors should also be examined from time to time, throughout their whole length, to make sure that all the joints are sound. Care should also be taken that the earth in which the terminating plate is buried is kept thoroughly moist. If any of these particulars be neglected, the conductor will be practically useless, and will afford no protection to the structure.—Abridged from Longman's Magazine.


IN examining the personal records of men who have contributed to the advancement of human knowledge, one of the features most frequently noticed is the necessity to meet adversity in early life. Perhaps it is but little less frequently the case that they are compelled throughout life to content themselves with a minimum of pecuniary reward for the mental work which meets due appreciation only after its final close. The thirst for discovery, the craving after truth, apart from all considerations of emolument, exist germinally in every young human being; but the rewards that the world gives for brain-work, other than what is directed toward the discovery of truth, are sufficient to determine most men and keep them occupied in fields other than scientific. Native bent, if fortified with force of character, finds its channel in time, whatever may be the accidents of childhood; and uncongenial occupation has been the lot of many who have used it as the basis of future renown.

Quite a number of those who have achieved distinction in physical science have, in early life, or throughout life, given a considerable share of attention to the mechanical details involved in constructing the instruments needed for investigation. Newton began in youth the making of machines, and his skill as a