Chro-nom'e-ter-es-cape/ment. The chronometer-escapement was invented by Berthoud, and improved by Harrison, Arnold, Earnshaw, and Dent. It is the most perfect, delicate, and satisfactory in its operation, of all the escapements. It is also kept more carefully, at least in marine chronometers, as the gimbal-joint hanging enables it to maintain a constant position relatively to the horizon, and it is carefully guarded from jars.

There are several points which distinguish it from other escapements, and several which it has in common with one or more of the others.

Fig. 1286.

P

The piece carrying the detent-pallet is a spring, and its motion to free the tooth of the escape-wheel is by the contact of a pin or tooth on the verge with a secondary spring attached to the former. As the balance oscillates in the direction of the arrow, its tooth V comes in contact with the secondary spring a, and presses the lever, so that its tooth T is freed from the tooth of the escape-wheel. A ruby pallet P on the verge receives the impact of another scape-tooth, and the balance receives its impulse thereby. As the balance returns, its verge-tooth V presses past the spring without moving the lever which rests against a stop. The impulse is commu-. nicated from the scape

Chronometer-Escapement.

wheel direct to the balance-arbor, as it is also in the duplex movement, not as in the lever movement where a pivoted lever intervenes.

Arnold's chronometer-escapement is substantially the same; a secondary spring attached to the spring-lever is made effective in vibrating the latter when moved in one direction, and in the other is so pliable as to allow the verge-tooth to pass freely. As just explained, the stroke which raises the springlever withdraws the detent from the tooth of the scape-wheel, and at the same time that this tooth escapes, another strikes a pallet on the arbor of the balance, and restores to the balance-wheel the force lost during a vibration.

The free movement of the balance is only opposed at one point during a complete oscillation.

Chro'no-met/ric Gov'ern-or. A device by which a time-measurer set to work at a prescribed and equable rate is made to regulate the motion of an engine. Invented by Wood and improved by Siemen. Chron/o-scope. Invented by Professor Wheatstone in 1840, to measure small intervals of time. It has been applied to ascertaining the velocity of projectiles. In Pouillet's chronoscope, a galvanic current of very short duration makes a magneticneedle deviate, the duration of the current being measured by the amount of deviation; by this means as short a time as some thousandths of a second can be measured. Schutz's chronoscope was

CHUCK.

employed by the Ordnance Department at the experimental firings at Fortress Monroe. The apparatus, operated by electricity, is described as follows:- Two wire targets are placed, one about twenty yards from the gun, and the second about the same distance farther on. These are connected by a fine insulated wire with the instrument, which is about 400 yards in the rear of the ordnance. The instrument is adjusted on a plan similar to an electro-ballistic machine. When the shot is fired, it cuts the wire in the first target, and then in like manner cuts the wire in the second target, the instant each wire is severed being recorded by the instrument. The interval of time occupied by the ball in passing from one target to the other furnishes the data for obtaining the initial velocity of the shot.

Noble's chronoscope is used for measuring the velocity of the shot during its passage through the gun. The ball presses upon a series of disks which in moving break or make electric connections, which are recorded on a rapidly rotating disk which has a known rate.

Chrys'o-type. (Photography.) A process by Sir John Herschel in which a sheet of paper is satuated with a solution of ammonio-citrate of iron dried in the dark. Exposed in a camera or printing-frame, the faint picture is developed by brushing over with a neutral solution of chloride of gold washed in water repeatedly, fixed by a weak solution of iodide of potassium, and then finally washed and dried. Chrys-tal'lo-type. (Photography.) A name given to a kind of picture on a translucent material. Opalotype.

Chuck. 1. An appendage to a lathe. Being screwed on to the nose of the mandrel, it is made to grasp the work to be turned. There are several varieties, as

rafid cleft to the end of a cylindrical tube, whose other end screws on to the threaded mandrel of the lathe-head. The object to be turned is thrust into the chuck, expanding the quadripartite socket. bis Beach's patent drill-chuck. c, center-drill chuck.

d, Warwick chuck.

e, Morse's adjustable chuck.

A circular saw of small diameter may be mounted on a lathe-chuck ƒ, which has an axial tenon to fit the hole in the saw, and a central screw or nut to fix the same.

Opticians use this mode for the small, thin saws with which they cut the notches in the tubes serving as springs in pocket-telescopes.

Carvers in ivory mount their saws in a similar manner. The saws for cutting the nicks in screwheads, and those for making slits in gas-burners, may be chucked or mounted on a mandrel.

The small, wooden mechanism for the interior of pianos is cut by saws similarly mounted.

g is a scroll chuck with three radially adjustable dogs.

h is a planer chuck.

i is a screw chuck.

k is an independent jaw chuck.

The eccentric chuck is designed for changing the center of the work, and consists of two principal pieces; one attachable to the mandrel of the lathe and the other adjustable in a plane at right angles to the axis of motion, in a dovetail groove of the former piece. The sliding-piece is moved by a set

screw.

The elliptic or oval chuck was invented by Abraham Sharp, and consists of three parts, the chuck, the slider, and the eccentric circle. The chuck is secured to and partakes of the circular motion of the mandrel. In front of the chuck is a dovetail groove for the reception of a slider, from the center of which projects a screw to which the work is attached. As the work turns round, it has a sliding motion across the center which generates an ellipse. The sliding motion is produced by an eccentric circle or ring of brass fastened to the puppet of the lathe close to the collar in which the neck of the mandrel runs.

A straight-line chuck is used in a rose-engine when the patterns are to be made to follow a straight instead of a circular direction.

A geometric chuck has a radial slider to which the work is attached, and this is so governed as to give a combined circular motion and radial oscillation to the work relatively to the tool. See GEOMETRIC-LATHE; ROSE-ENGINE.

Fig. 1288 shows three forms of lathe-chucks having jaws to grasp the tool or the work, as the case may be.

a. The stock of the chuck terminates in a conical, threaded head, which opens or closes the jaws, which are threaded, and slide in grooves in the conical shell.

Chucks.

CHURN.

b. The nut has a conical opening in the end which operates against the inclined backs of the jaws, to clamp them upon the drill; when relieved they are expanded by springs.

c. This chuck belongs to that class which is constructed with screws for the purpose of operating the jaws. It is provided with a double screw, the pitch of one being just half that of the other, to operate the jaws simultaneously in opposite directions so that they will approach or recede from the center at equal speed, thereby forming a self-centering mechanism.

2. (Nautical.) d is a warping chuck in which hawsers or ropes run. Friction rollers prevent the wearing of the rope. It is used on the rail or other portion of a ship's side.

Chuck-lathe. A lathe in which the work is held by a socket or grasping device attached to the revolving mandrel of the head-stock. It is used for turning short work such as cups, spools, balls, and a great variety of ornamental and useful articles. See CHUCK.

Churn. A vessel in which milk or cream is agitated to induce the separation of the oily globules from the other portions.

The ancient mode of making butter was probably the same as practiced by the Bedouin Arabs and the Moors in Barbary at the present day. The cream is placed in a goat-skin and agitated by hand or by treading it with the feet.

The butter and honey mentioned by Isaiah vii. 15, is to this day an article of food in the East. The butter and honey are mixed and the bread dipped in it.

The word chamea, rendered butter in our translation of the Bible, seems to have referred to several forms of milk and its productions, such as sweet or sour milk, cream, thick milk, curd, or butter. The latter is perhaps the most infrequent form of its use, but is evidently intended in those passages where the article is used for anointing. It was "butter of kine and milk of sheep" that made Jeshurun "wax fat and kick." Abraham "took butter and milk and the calf which he had dressed and set before" three stranger visitors. Sisera "asked water, and" Jael the wife of Heber the Kenite " gave him milk; she brought forth butter in a lordly dish" before she nailed him to the ground with a tent-pin and a hammer. Job refers to the time when he anointed his feet, or as he expressed it, "washed my steps with butter, and the rock poured me out rivers of oil." "Surely the churning of milk bringeth forth butter." The reader can pick out the various probabilities of each case for himself. It must be mentioned, however, that the word rendered churning may be just as correctly rendered pressing, and may refer to the pressing of curd to rid it of the whey. Sweet milk occupied but a limited space in the Oriental economy, ancient or modern. It necessarily became soon soured, and they accepted the situation. The leban (coagulated milk) of the Arabs was and is the usual form in which milk is used.

The Turks yet show their Tartar origin in the preference for sour over sweet milk.

We have a mention of butter in the description of the Scythians by Herodotus (b. 484 B. C.). "These people," says he, "pour the milk of their mares into wooden vessels, cause it to be violently stirred or shaken by their blind slaves, and separate the part that arises to the surface, as they consider it more valuable and more delicious than that which is collected below it." This is evidently butter.

Hippocrates (460 B. c.) describes the process

butter.

The references to butter are occasional only; by Aristotle, who speaks of it as the oily part of milk; by Strabo, who speaks of its use by the Ethiopians; by Plutarch, who speaks of a Spartan lady anointed with butter, and smelling so loudly that Berenice, her hostess, positively could not stand it. Berenice on her part smelt so strongly of rancid oil, that the Spartan was happy to leave.

Dioscorides and Galen refer to the use of butter as a substitute for olive-oil as a dressing for table use or for leather. Lamp-black, obtained by the burning of butter, they recommend for an eye-salve.

Pliny describes the use of butter and cheese by thebarbarous" Germans. The Romans used butter for anointing, the Germans for a hair-dressing, the Egyptians for burning. None of them probably knew the taste of good, hard, clean butter.

The Christians of Egypt used butter instead of oil in their lamps in the third century. It was easier to raise cattle than olives, apparently, in that land where it is said it now costs less than three dollars to raise a child to maturity.

The Arabians and Turks have a preparation of curdled milk, called leban by the former and yaourt by the latter, which they preserve in bags. In appearance it resembles pressed curds after they have 'been broken by the hand; mixed with water it becomes a cooling drink, and is said to be wholesome and serviceable in febrile diseases. It probably formed the last meal of Sisera.

Fresh yaourt is much used as food by the natives, and Europeans soon acquire a taste for it.

The butter received at Constantinople from the Crimea and Kuban is not salted. It is prepared by melting in large pans and skimming off the impurities which rise to the surface. Butter thus prepared is called ghee in India. It is used for food by some castes and for anointing. Ghee is used to soak the wood on which the victim of the suttee is sacrificed.

The classes and varieties of churns are so numerous that justice cannot be done to the subject within admissible bounds. The following classification, with an example of each, will afford a glance at the distinctive kinds.

1. The plunger churn. a represents the verticaldasher plunger churn. A spring assists in the recoil or lifting motion. Rotation of the dasher may be given by a spiral on the stem, or by giving a spiral set to the blades.

b is a horizontally operated dasher churn. 2. Barrel churn. e has a pair of dashers revolving in different directions by distinct cranks. In a modified form, the barrel is mounted on trunnions and is itself rotated.

d has a stationary barrel and one rotated dasher. 3. Box churn. e has two dashers revolving at different speeds. The inner dasher is driven by the crank-axis direct; the outer one by an internally geared wheel, a pinion, and a third wheel on the sleeve which carries the dasher. The arrangement of wheels is shown at e'.

CHURN.

4. Tub churn. f has a vertical dasher-shaft rotated by wheel and pinion from the crank-shaft. g has two dashers rotating in different directions, one driven by the central axis and the other by the

sleeve axis. Each axis has its own pinion, driven by a common wheel.

h has a pair of parallel dashers driven in contrary directions by the master-wheel, which acts upon the respective pinions.

5. Atmospheric churn. i; as the dasher rises, the valve on the upper end of its stem falls and admits air, the valve on the hollow guide-rod closing. As

Churn-pow'er. A motor for driving churns or churn-dashers to agitate the milk or cream.

Animals, such as dogs, sheep, or goats, are employed in treadmills or slatted platfroms on endless belts.

The power of descending weights, springs, wind or water driven wheels, etc., are used.

Chute. An inclined trough.

On a moderate scale it forms a leader, or feeder for materials or blanks, to machines.

On a large scale it leads water from a penstock to a water-wheel, or an inclined plane down which logs are passed from a higher level to a lower one. These are sometimes in mountainous countries for land transportation, and sometimes are the links of a slack-water system, as on the Ottawa; called slides. Ci-bo'ri-um. (Architecture.) An insulated arched vault resting on four pillars, as that over the high altar of a church.

Ci'der-mill. A grinder for apples generally, in practice, including the press in which the pomace is pressed.

The common cider-mill a, used in the Southwest of England, is on the principle of the Chilian mill, being a cylindrical stone weighing one or two tons, and rotating in an annular trough of masonry.

The axis of the stone is connected by arms to a sweep which is pivoted on a central post and revolved by a horse. In some cases the central space forms compartments for holding apples. The roller is from 2 to 4 feet in diameter, and 9 or 10 inches wide at the face. The trough is somewhat wider at top by the inclination of its outer side, to allow freedom of motion to the runner. The bed is from 9 to 12 feet in diameter.

Cider-mills in England are also made with hollow iron fluted rollers, working in pairs and meshing into each other.

In Ireland the apple is crushed between wooden cylinders studded with iron teeth; the pomace is afterwards pounded with wooden pestles.

The cider-press of the West of England is a modification of the common screw-press. The pomace is enclosed in a bag of haircloth about 4 feet square, and holding two or three bushels. These are heaped over each other in the press, to the extent of fifteen or eighteen bags. These yield from 100 to 200 gallons of juice, according to number and the succulency of the apples. The press-screw is manipulated by a lever.

The cider-mill (b) used in the South of France has a platform of boards framed together and is traversed by a conical frustum of cast-iron whose axis is hooked to a rotating eye in the center of the platform and is swept around by manual power, crushing the fruit in its passage.

The mill c has a grinding-wheel and concave, and an apron which carries the pomace between two pressing rollers and a wire-screen cylinder through which the juice runs.

d has alternate grinding portions and a doubleheaded piston, which presses the pomace against the ends of the box alternately. One end of the box is filling while the other is pressing.

CIGAR.

Fig. 1291.

Cider-Mills.

e has a metallic grinder and a hoop with a screw. f has a grinder and presser, which may be acting simultaneously. A hoop filled with grindings is pushed from below the hopper to beneath the screw, and an empty hoop substituted beneath the former. Ci-gar'. A roll of tobacco-leaves for smoking. It

Fig 1292.

Cigar-Bundler.