"This is a question, my dear, that will require some little time and thought to answer properly. In the first place, you must understand that light travels very much faster than sound and that sounds do not reach you until some time has elapsed, if you are a little distance away. You see a flash of lightning, and a little while after you hear the thunder; and if you count 1, 2, 3, in the ordinary way, between seeing the flash and hearing the thunder, you may be fairly satisfied the source of the thunder is well on to three miles away. This, of course, is not exactly correct, but approximately so. Every time you count one, it stands for a mile. According to science, light travels 186,000 miles a second, while sound only travels at the rate of 1,090 feet per second at a temperature of 32 degrees Fahrenheit, or freezing, its velocity being increased at the rate of one and one tenth feet per second for every degree above this temperature. So you see light travels nearly a million times faster than sound, and this accounts for your seeing the puffs quite a little while before you heard the 'toots', as you call them. There are many curious and interesting things about light and sound which I'd like to describe to you sometime.
"Sound travels in dry air at 32 degrees, 1,090 feet per second, or about 170 miles per hour; in water, 4,900 feet per second; in iron, 17,500 feet; in copper, 10,378 feet; and in wood, from 12,000 to 16,000 feet per second. In water, a bell heard at 45,000 feet, could be heard in the air out of the water but 656 feet. In a balloon, the barking of dogs can be heard on the ground at an elevation of four miles. Divers on the wreck of the Hussar frigate, 100 feet under the water, at Hell Gate, near New York, heard the paddle wheel of distant steamers hours before they hove in sight. The report of a rifle on a still day may be heard at 5,300 yards; a military band at 5,200 yards. The fire of the English, on landing in Egypt, was distinctly heard 130 miles. Dr. Jamieson says he heard, during calm weather, every word of a sermon at a distance of two miles. The length of the sound waves in the air is sometimes many feet, while the length of the longest light wave is not more than .0000266 of an inch; it is no longer a mystery why we can hear, but cannot see, around a corner."
The children were greatly interested by these familiar marvels and made their father promise that he would resume the talk some other evening and tell them about thermometers and barometers.
The late afternoon next day was taken up with an excursion on the Caroline down the river to Newark, where Fred induced his father to purchase a full soldering outfit, as the boys wanted to try some plumbing and soldering work. There had been a plumber at the Gregg home nearly all that day doing repair work of various kinds, and Fred, who had watched the workman, concluded he could have made the repairs himself if he had had the proper tools.
An hour or two in the city, then a pleasant sail home, proved a fine ending for a day's labour.
The next day, after school, George and Jessie assisted their mother "making garden," planting flowers, trimming bushes, and destroying weeds, while Fred gave the Caroline another coat of varnish, and finished painting his little workshop, which now looked very snug and tidy. He soldered up all the leaks in every kitchen utensil he found defective, much to the delight of his mother and the maid. Fred found many things about the house wanting more or less attention, so he determined to try to put them in order. He discovered that to make a good job of soldering, he must first make the metal to be fastened together, perfectly clean and free from rust, dirt, or grease, the parts around the leak being scraped bright and smooth. He found some little difficulty in getting the solder to the exact place he wanted. In the outfit his father bought him, was not only a soldering iron,—which is not iron but copper—but a scraper, a lump of solder, a box of rosin, a piece of chamois leather, a bottle of muriatic acid, and a piece of sal-ammoniac, to be crushed fine and dusted over any surface that is to be finished bright. Fred had no trouble in soldering holes of small size in teakettles, tins, or such things as he could handle easily, for the impaired portions could be placed in a horizontal position before him and the solder applied readily. A leak in an upright water pipe in the shed, however, gave him a hard time, for he could not get the solder either to run up hill or to stay on the place where it was put. He got over this difficulty, however, by making a clay dam, a "tinker's dam"—mixing clay until it was soft, then winding a strip of it around the pipe just below the leak and applying the solder until the hole or crack was entirely covered, when a good solid job resulted. Of course, before applying any solder, all the water was drained from the pipe, and the defective part was thoroughly scraped. When the work was done, there was an edge of solder left projecting from the pipe, which Fred rasped away with a course rasp, leaving just enough solder to cover the leak properly. He then sandpapered the work and it looked almost as "good as new."
It is easy enough to solder across the work when level, even if the article being soldered is round, because the metal can be worked across the top and down the sides; but on the under side, it may be necessary to make use of a clay dam. A plumber's work covers a lot of things, among which may be mentioned metal roofing, wall flashings, water-pipes of all kinds, drain connections, hot water and steam fittings, hot-air and ventilation fittings, stove and range settings, and many other things connected in some way or another with the foregoing. Many times an offensive odour is noticeable in the cellar, or near the line of drainage, and it is often difficult to locate the source, so that expensive excavations are made before the trouble is remedied. Plumbers and drainage men often use what is termed "the peppermint test," to find where the leakage exists, and this is particularly suitable for the examination of existing soil pipes and drainage fittings. This test consists in pouring a small quantity of oil of peppermint or other substance possessing a pungent, penetrating, and distinctive odour, into the pipe or drain. The defective pipe or joint is then located by the escaping odour.
It is very important that defects of this kind should be located and repaired immediately, for odours emanating from drains or soil pipes carry with them germs of the kind most dangerous to human health and life.
Some taps in the bath room and over the kitchen sink were not working freely, and others were "dropping" a little. Fred, after cutting off the water from the main, unscrewed these and put new rubber washers in some, wound cotton twine around the plugs of others, and made the tight ones work easy by removing worn out washers and cut strings. He also fixed the hydrants on the lawn in the same manner, and made all the taps in and about the house work tightly and smoothly.
When Mr. Gregg arrived home, Fred told him all he had done, showing the tin pans and the leaky pipe he had soldered, and he straightened up with pride at being told that he was already "quite a plumber."