SECRETARY'S REPORT FOR 1874-75.

There have been held during the year twelve meetings of the Society of Arts, at which various subjects of practical importance were discussed.

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At the meeting of Nov. 12, 1874, Mr. Robert B. Forbes read a paper on the "Tracks for Atlantic Steamers," as a report of his doings as representing the Institute in conference with the Committee of the Social Science Association in regard to the Maury Lanes." He concludes by saying "Now that we have a steamer leaving Europe and North America on the Atlantic every five or six hours, no amount of argument should be necessary, and no pains omitted, to induce all to adopt the Maury Lanes. Unless steamers adopt some definite lines for going and returning, recent disasters show that size, speed, and elegance of ship may not save from collision accompanied by great loss of life.

Within a few months the loss of over four thousand human lives shows the necessity for more means to save life, and better arrangements to prevent accidents from fire, collision, etc. He advocated more and better boats, rafts, life-buoys, mattresses and belts, and various buoyant contrivances carried by the ship herself; all of these, however well-contrived, may yet be useless if the crew are not rendered familiar with their use by frequent drilling. Any properly constructed raft, well supplied with food and water, would be very likely to save its passengers if in the track of steamers crossing the Atlantic, as the lines, if (xvii)

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adopted, would be only a hundred miles or so wide; a sailing vessel, too, disabled, would know where to send her boats to be sure of meeting a passing steamer. The ship herself should be made invulnerable to ordinary ocean casualties, by double bottom as far as the load line, iron decks, water-tight compartments, boiler spaces cut off from other compartments and from coal bunkers below the load line, donkey engine and boiler far away from ordinary casualties of the main machinery, and pumps so fitted that steerage passengers could be used for their working. In other words, make the ship a life-boat.

He advocated better means of detaching boats from their tackle, the Ammen wooden raft, or the Perry or Monitor raft of vulcanized rubber, the swinging davit, and the substitute of the centre-board for a keel in boats. Means for throwing a line two hundred or three hundred yards should be on all passenger ships and men-of-war.

At the same meeting, Mr. H. P. Langley read a paper on "Artificial stone, and its uses," illustrated by specimens. He confined his remarks to that made by the use of hydraulic cements, lime and magnesia, including the Ransome, Frear, Beton-Coignet, and Sorel processes. Stone made by any of these processes has not come into general use in this country as building material; a few buildings, in Boston and vicinity, have been erected wholly or in part of the Frear stone, and the Beton-Coignet has been used to some extent in foundations, piers, etc.; a stone embodying strength, durability and elegance can be made from Portland or the best American cements and pure silicious sand. Many useful and ornamental articles for domestic use are made by the Sorel process. He also exhibited and explained several grinding machines.

Dec. 10. Mr. John C. Hoadley, of Lawrence, read a paper, illustrated by numerous carefully made drawings, on the "Indicator Diagram and its Interpretation.”

The indicator, an instrument invented by James Watt, to show the operation of steam in his engines, was the forerunner of a large class of philosophical instruments for noting and

recording vibrations, from the pulsations of an infant's heart to the throes of an earthquake, and velocities, from that of a gentle breeze to that of a rifle projectile or a ray of light.

The diagram, credited to the same inventor, in which forces are exhibited to the eye under the form of curves, by abscissæ proportional to times, spaces, or volumes, and ordinates proportional to pressures, stresses, strains, or any other similarly related magnitudes, is applied to almost all subjects to which the human mind directs its attention.

The indicator is a small, subsidiary, reciprocating engine, attached to the cylinder of a steam engine, or other similar machine, sharing the pressures, expansions, and forces of the chamber with which it communicates; and expending the work developed in its own cylinder in compressing a spring, and in giving motion to a pencil or marking point, which traces on a slip of paper, moving under it with a known velocity, a curved line which, properly interpreted, discloses much concerning the action of the steam or other fluid in the engine, the adjustment of valves, the adequacy of ports and passages, the tightness of packing, the dryness of the steam, the quantity expended per unit of force, and other important points bearing on the question of economy.

After describing the best indicators in use, he showed how the diagrams were made, and how interpreted; he took up the subject mathematically, analyzing observations of his own made during several years, and drew from them practical lessons of great value.

Dec. 24. Mr. George Woods, of Cambridge, made a communication, illustrated by a model worked by steam and water, on his new process for drying lumber and other materials in a natural and rapid manner. The old process of drying lumber in the open air requires from six to ten years, and the consequent loss of time and capital stimulated inventors to devise quicker processes, and various drying rooms have accordingly been in use, with more or less success. In the usual method of forcing a current of air through a room heated to about 150°

Fahr., from partial ventilation the drying was found to be imperfect, causing irregular shrinkage and consequent inequalities in the wood; the steam pipes were carried under the lumber, and the air forced to pass over it, drying the outside first, the interior remaining damp from the air being saturated with moisture. He uses steam pipes under the lumber, but the moisture which is driven by the heat into the containing chamber, instead of being carried off with great loss of heat by the ventilating current, is condensed by cold water constantly running in pipes through the chamber into a grooved channel below, by which it escapes. The moisture is thus gradually, uniformly, and constantly withdrawn from the wood, which dries regularly, without strain on the outside or cracking on the inside. He claims that he can accomplish in six days what the ordinary drying room requires three weeks for, and with much better results; he saves three quarters of the time and utilizes all his heat, and the moisture once out of the wood can not get back. Mr. N. M. Lowe made some remarks, illustrated by photographs, on the "Leaning Tower of Pisa," adding his testimony in support of the general belief that the tower was not built so, but has sunk from imperfection in the foundation, aided by the yielding character of the soil. Its height is nearly two hundred feet, and its diameter thirty feet; it leans from the perpendicular about thirteen feet, but, as the centre of gravity falls within the base, the structure will not fall unless there be further sinking of the foundations.

Mr. H. P. Langley made some remarks on various mechanical devices, which have of late years made their appearance in this community, achieving for their inventors a short-lived success, and for their users and purchasers vexation and pecuniary loss, with especial reference to steam boilers.

Jan. 14 and 28, 1875. Mr. H. McMurtrie presented portions of a wooden casing which had surrounded a steam pipe at a hotel in this city, showing how wood may be charred by steam used for heating purposes at a distance of an inch from the iron

pipe. Many mysterious fires may owe their origin to this

cause.

Mr. Thomas S. Hall, of West Meriden, Conn., made a communication, illustrated by an extensive series of working apparatus, on his system of automatic electric railway signals, for the prevention of accidents from head and rear collisions, misplaced switches, open drawbridges, and railroad and highway crossings, dispensing with the steam whistle, and lessening the number of workmen required, an automatic electric power taking the place of careless and forgetful human agents. The usual way has been to allow a certain interval of time to elapse before one train is permitted to succeed another. This system is exceedingly defective, as, if an accident or detention occur, the engineer behind has no reliable means of knowing where the preceding train is; even the electric telegraph, from the carelessness or inexperience of operators, may, as in a recent case, fail to give warning in time to prevent collision.

Mr. Hall's system substitutes for this an interval of space, trains being kept a mile apart as indicated by his automatic signals, rendering collision impossible, avoiding the multiplication of tracks, and allowing the much more frequent despatching of trains. The block system, used in England, requires a great number of men day and night, and many accidents have happened under it.

In Mr. Hall's system the road is divided into sections of about a mile in length, at the ends of which are placed two signals, one red, to denote danger; the other blue, signifying caution. When all is right, the red signal should be out of sight, and the blue signal exhibited. As the train passes the first, it raises it, at the same time removing the blue signal, which is about 1000 feet ahead. The red signal then prevents the next train from approaching too near, while the blue signal shows the engineer that the red signal has been displayed. About 600 feet beyond the blue signal, the train reverses the signals of the previous section, or those of a mile and a third back, thus allowing the next train to approach.