Inventors at Work, with Chapters on Discovery

by George Iles

Short Cuts in Engineering.

Rock may be so hard as to withstand a drill of the hardest steel; then the engineer pours an acid of the necessary dissolving power. A water pipe may freeze at a point difficult of access; it is thawed by the warmth created by an electric current. A surveyor has to reduce to square feet the irregular area of a factory site or a garden plot; around the edge of his diagram he runs a planimeter, it tells him automatically what surface it has surrounded in its excursion. If he has no planimeter, a delicate balance will serve just as well. Let him take a piece of paper, uniform in thickness, and cut it into the shape of the area in question. In weighing the diagram with care he learns its superficies because he knows the weight of each square inch or foot of the paper. Pumps for ages have exercised the wit of inventors who have devised wheels, screws, pistons, and scoops of every imaginable form. M. Giffard boldly discarded all moving parts whatever and in his injector, actuated directly by a blast of steam, provided a capital means of sending water into a boiler.

A generation ago engineers of eminence were attempting the transmission of energy in a variety of ways. Ropes and wire cables were installed for considerable distances in Germany and Switzerland; in France there was an extensive piping of compressed air, still in evidence at the capital; and water under high pressure is to some extent to-day employed in London. All these schemes, together with the old methods within a shop itself of taking motion from motor to machine by belt or chain, have been wiped off the slate by the electrical engineer. With a tax of the lightest he carries for many miles in a slender wire a current whose energy takes any form we please,—not only mechanical motion, but chemical action, light or heat. Can simplification go farther than this, or the future hold for us another gift as golden?

Painting by Immersion.

Binders, reapers, and mowers have irregular surfaces which it would be costly to paint by hand. Even to use the painting machine which works by compressed air would be somewhat expensive. In the painting shop of a factory both brushes and nozzles are banished. The large floor is fitted up with a series of tanks: overhead are the lines of a suspension railway. The tanks are filled with paint, the articles to be treated are run in on the rails, lowered automatically for their bath, and then carried off to drip and to dry. In this way a large and complicated agricultural machine can be painted in a few seconds. Were deep tanks employed, this method would squeeze oil, varnish, or paint into the pores of wood very thoroughly.

Churning the Air in a Telescopic Tube.

Astronomers suffer much from the inaccuracy of the images viewed in their telescopes in consequence of the disturbances in the atmosphere, common even in clear weather. Hence observatories have, of late years, been established at Arequipa, Peru, and at other stations where the atmosphere is calm and little disturbed by currents. On investigation Professor S. P. Langley, of Washington, discovered that a good deal of the perturbation of telescopic images arises from currents within the telescopic tube itself. As a remedy he adopted the heroic, yet simple, measure of thoroughly stirring up the air in the tube by a blower or other suitable means. Its air, thus brought to uniformity of condition, yielded images much clearer than those usually obtained. Especially convincing in this regard are capital photographs of artificial double stars whose beams were entirely confined within a horizontal tube in which they traveled to and fro through no less than 140 feet of churned air. These pictures showed that the disturbance within the tube itself appeared to be wholly eliminated by the device of vigorously stirring the air column.

This recalls a method of shipping pianos in refrigerator cars. The instruments are carefully brought to the temperature of the car, which is maintained at about zero, Centigrade. When the pianos arrive at their destination they are slowly warmed to the temperature of common air. No matter how long they have been cold, they suffer no hurt; for it is not cold, or moderate elevation of temperature, that does harm so much as uneasy fluctuations from one to the other.

Loose Cards Replace Books.

When one visits a public library, the title of a particular book is found in the catalogue in a moment. Every book as acquired has its title written on a card, and thousands of such cards are placed in alphabetical order, just like the words in a dictionary. A thousand cards or so begin with “A,” and are placed in a drawer marked “A,” which stands first in the case, and so with the rest. There is always room to spare in each drawer, so that when a card for a new book comes in there is space for it. It was a happy thought of a Dutch inventor when he thus made an index which can always be alphabetical, easily added to or subtracted from, simply because its leaves are mere cards with the binding of a common index omitted. In public libraries the catalogue-cards are of standard sizes, so also are the drawers in which these are disposed. In fact library-furniture of all kinds is to-day thoroughly standardized in its styles and dimensions, making it easy to fit up or to extend a library whether public or private.