the ship as the soundings are made while the steamer is running at full speed. To make a sounding, a small quantity of a solution of sulphate of iron is poured into the tube, and the prepared glass tube is plunged in this, so that the open end is sunk in the solution and inclosing a small quantity of air within the tube above the solution. The cap is fitted on the top of the brass tube, and the sinker is let fall from the stern. The wire runs out at great speed, and when it slackens, or reaches the estimated depth, a brake is applied, and, by the aid of a crank, the wire is wound in without much effort and is coiled on a reel made for the purpose. The wire offers very little resistance to the water, and the whole operation seldom takes more than a few minutes. On recovering the brass tube, it is found that the sulphate of iron has been forced up inside the glass tube by the pressure of the water, and by chemical action staining the inside of the tube a deep blue. On comparing the stained part of the tube with a gauge, the depth of the water may be ascertained in fathoms by the proportion of the stained part of the tube, and the tube thus becomes a permanent record or "log" of the pressure, and hence of the depth of the water. To make another sounding, a fresh tube is used, and a stock of prepared glass tubes must be taken on the voyage.

These tubes can be afterward cleaned and recharged with the red prussiate of potash at a slight expense. The apparatus is light, strong and durable, and has been found to work accurately under the rough usage of a voyage.

Electrical deposition of Metals.

FROM a number of experiments in the electrical deposition of metals recently made by Professor A. W. Wright of New Haven, it has been found that films of gold, iron, bismuth, silver and other metals can be laid on glass in a manner that promises to give even more valuable results than can be obtained from the common electro-plating process. The work is carried on within a hollow glass vessel from which the air is excluded. The two ends of an induction coil are brought into this vessel, and to the negative pole of the coil is attached a small piece of the metal to be deposited. The object to be platedglass or silver-is suspended between the two poles of the coil. By the aid of a battery, a powerful spark is sent through the coil, and the gold or other metal is partially vaporized by the heat. metallic vapor condenses, like dew, on the cold glass, and immediately cools, forming a metallic film of exceeding fineness upon the glass. A second spark again vaporizes the metal, and another film condenses on the first coat. In like manner, any number of films or coats are laid one over another till the desired thickness of deposit is obtained. Metallic films thus laid on glass are of excessive fineness, and cling to the glass with extreme tenacity. The metallic deposits obtained by this process will be valuable in a variety of scientific investigations, and will doubtless prove useful in the construction of mirrors for telescopes, heliostats and other optical instruments. Films of gold of an esti

This

mated thickness of only 0.000183 millimeters have been obtained, and it is suggested that these exceedingly thin sheets of metal may be useful in investigating their character in transmitted light. Such films of gold, held before the light, show the characteristic green color of gold. Professor Wright's process will undoubtedly lead to new and useful improvements in the art of depositing metals. The mirrors thus made from vaporized iron, platinum or silver are of a remarkably pure and brilliant char.

acter.

The Aleurometer.

THIS instrument is designed to take the place of some of the more simple though perhaps inexact methods used in testing flour. It serves to measure the elasticity of the gluten in flour by recording the expansion of the gluten under the influence of heat and moisture. Wheat for baking depends on the elastic quality of the gluten; flour for macaroni is chiefly valued for the ductility of the gluten, and the aleurometer is thus chiefly useful in the hands of bakers and dealers in flours designed for domestic consumption. The instrument consists of a brass tube 3 centimeters in diameter, and about 12.7 centimeters (5 inches) long. This is provided with a cap that may be screwed to the bottom and that also serves for a base, and another cap is permanently fixed to the top. Inside the tube is a piston, fitted accurately, and provided with a piston-rod that extends upward through an opening in the top of the tube. The whole length of the tube is divided into fifty divisions, and the piston-rod is graduated from twenty-five to fifty of the same division. In use, 30 grammes (about 1 oz.) of flour is selected and made into a paste, with 15 grammes of water. After kneading, this is washed in a stream of water to remove the starch, and is then compressed to drive out the surplus water. A sample of this crude gluten is then weighed, and 7 grammes are taken out and rolled in starch to make a roll that will fit the aleurometer. The cap is removed from the base of the tube, and the inside of the tube is smeared with butter, and the roll of gluten is then inserted so as to fill just half the length of the tube or the space below the piston when it is at rest and leaving the piston pressing on the roll of gluten. The instrument is then placed in an oven, kept at the usual baking temperature. Under the heat, the gluten will expand and raise the piston, thus showing its degree of elastic expansion by the marks on the piston-rod that projects above the instrument. Good flour is said to give gluten that expands fifty per cent. beyond its original bulk. Bad gluten does not swell at all, and remains viscid and sticks to the tube, besides giving out a disagreeable odor. Good flour in this instrument gives the sweet smell of hot bread. For dealers who have no facilities for baking, the aleurometer is arranged with an oil-bath heated by a lamp or gas jet, and in this bath the gluten may be raised to any desired temperature, and to regulate this, a thermometer is attached to the apparatus.

Carrier-Pigeons in Fishing.

THE herring-fishing carried on in boats at night involves a certain amount of lost labor from the fact that the fish must be cured immediately on the arrival of the boats with the catch in the morning. No estimate can be made of the amount of catch to be brought in, and a large force must be maintained on shore to prepare for any extra supply that may arrive in, and in case of light fares, much of this labor is wasted. To obviate this uncertainty and to give prompt information on shore of the probable return of the boats and the amount of their load, carrierpigeons are now employed. A bird is taken out in each boat, and when the nets have been hauled in and the amount of the catch is ascertained, the bird is let loose with the information on a slip of parch

ment tied round its neck. The bird at once "homes" and quickly delivers its burden at its owner's residence. The direction of the wind, the position of the boat and its prospects for the return voyage and other useful information may thus be sent ashore, and in case of unfavorable weather, directions may be sent to guide the tug-boats that go out to bring in the fleet. In our cod-fishing on the Banks, "homing pigeons" might often prove of the utmost value, both in stating the position of the fleet, and in preventing loss in case of disaster, and in guiding steamers to the rescue of disabled boats. The use of parchment on the neck of the bird has several objections, and fine, light, oiled paper, carefully bound round one of the tail-feathers is thought to be a much safer way of sending dispatches by pigeon express.

Some New Models for Letter-writers. In the series of models for letters published in this department for November, there were some circumstances and contingencies likely to arise in ordinary American life, which were left unprovided for; and, therefore, at the request of many readers who feel the need of models to suit certain particular cases, the following additional forms have been prepared. It is hoped that they will prove to be adapted to the cases for which they are intended, and that the language of the epistles will not be found at variance with that of the ordinary "Complete Letter-writer."

No. I.

From the author of a treatise on molecular subdivision, who has been rejected by the daughter of a cascarilla-bark-refiner, whose uncle has recently been paid sixty-three dollars for repairing a culvert in Indianapolis, to the tailor of a converted Jew on the eastern shore of Maryland, who has requested the loan of a hypodermic syringe.

WEST ORANGE, Jan. 2, 1877. DEAR SIR: Were it not for unexpected obstacles, which have most unfortuitously arisen, to a connection which I hoped, at an early date, to announce, but which, now, may be considered, by the most sanguine observer, as highly improbable, I might have been able to obtain a pecuniary loan from a connection of the parties with whom I had hoped to be connected, which would have enabled me to redeem, from the hands of an hypothecater the instrument you desire, but which now is as unattainable to you as it is to

Yours most truly,

No. 2.

THOMAS FINLEY.

From an embassador to Tunis, who has become deaf in his left ear, to the widow of a manufacturer of perforated under-clothing, whose second son has never been vaccinated.

TUNIS, Africa, Aug. 3, '77. MOST HONORED MADAM: Permit me, I most earnestly implore of you, from the burning sands of this only too far dis tant foreign clime to call to the notice of your reflective and judicial faculties the fact that there are actions which may be deferred until too recent a period.

With the earnest assurance of my most distinguished regard, I am, most honored and exemplary madam, your obedient servant to command, L. GRANVILLE TIBBS.

No. 3.

From a hog-and-cattle reporter on a morning paper, who has just had his hair cut by a barber whose father fell off a wire-bridge in the early part of 1867, to a gardener, who has written to him that a tortoiseshell cat, belonging to the widow of a stage-manager, has dug up a bed of calceolarias, the seed of which had been sent him by the cashier of a monkey-wrench factory, which had been set on fire by a one-armed tramp, whose mother had been a sempstress in the family of a Hicksite Quaker.

NEW YORK, Jan. 2, '77. DEAR SIR: In an immense metropolis like this, where scenes of woe and sorrow meet my pitying eye at every glance, and where the living creatures, the observation and consideration of which give me the means of maintenance, are always, if deemed in a proper physical condition, destined to an early grave, I can only afford a few minutes to condole with you on the loss you so feelingly announce. These minutes I now have given. Very truly yours,

No. 4.

HENRY DAWSON.

From the wife of a farmer, who, having sewed rags enough to make a carpet, is in doubt whether to sell the rags, and with the money buy a mince-meat chopper and two cochin-china hens of an old lady, who, having been afflicted with varicose veins, has determined to send her nephew, who has been working for a pump-maker in the neighboring village, but who comes home at night to sleep, to a school kept by a divinity student whose father has been educated by the clergyman who had married her father and mother, and to give up her little farm and go to East Durham, New York, to live with a cousin of her mother, named Amos Murdock, or to have the carpet made up by a weaver who had bought oats from her husband, for a horse which had been lent to him for his keep-being a little tender in his fore feet-by a city doctor, but who would still owe two or three