The thermostatic incubator, its construction and management, together with descriptions of brooders, nurseries, and the mode of raising chickens by hand

Contents

PAAE

Construction of tke Incubator, ... 30

Preparations for Work, .... 49

Introduction

The Thermostatic Incubator furnishes an efficient and reliable means of hatching chickens artificially. It is the result of numerous experiments, and as its principal features have been thoroughly tested for seven seasons, and it has been successfully used in its present form for two, it is confidently offered for public use. It is adapted to hatch ducks* eggs, as well as those of chickens, the author having hatched with it an average of 250 chickens and 40 ducks annually ; which is as large a number as his family can dispose of. Partridge eggs have also been hatched in it, with perfect success.

As the experience of the author may be of service to others working in the same field, and a statement of it will enable the construction of the apparatus to be better understood, it may be worth while to give a sketch of his labors. The subject was taken up in 1873 as an amusement, and as a means of diverting the mind from the cares of an arduous professional business. The raising of fancy chickens had been a hobby for years, and the various published statements of the methods of hatching chickens artificially had been carefully studied. As the residence of the author was heated by steam, it was thought that a sufficiently equable heat could be obtained from the top of the steam boiler to do the work of incubation. Hence an incubator was constructed with two drawers, one above the other, and with the lower edges of its sides curved to fit the top of the brick casing of the steam boiler ; a thermometer was placed in this incubator, and it was found that there was sufficient heat for the purpose. The accounts of the various incubators made by others had informed the author that there were three things essential to successful artificial incubation ; viz., an equable temperature, ventilation, and moisture. Moisture had been supplied by Bonnemain and his successors, by placing pans of water in the incubator beneath the eggs. Ventilation had also been effected by admitting air to the lower part of the incubator, and allowing the hot or foul air to escape from its top. Following in the steps of his predecessors in the art, the author fitted his first incubator with a water trough beneath the egg drawers, and with holes for the admission of fresh air, which was distributed beneath the egg drawers by means of metal plates.

A ventilating hole also was made at the top, and was fitted with a damper valve, which was to be opened and closed for the purpose of varying the draught of air through the incubator and thus regulating the heat. The damper valve was operated by a very large alcoholic thermometer, holding half a pint of alcohol, which was closed to the air by an inverted syphon pipe containing mercury on which a float was placed ; and the float was connected with the ventilating valve. This alcoholic thermometer proved too sluggish for any practical use, and was abandoned after a trial of three days. A second attempt was made to operate the ventilating valve, and thereby regulate the heat, by means of a large mercurial thermometer, the bulb of which was of iron and contained a pound of mercury. This also proved to be too sluggish, as it required a variation of 20 Fahrenheit in the egg chamber to make it operate the valve sufficiently. A third attempt was made with a thermostat constructed of brass rods and glass tubes arranged like the bars of a compensation gridiron pendulum ; the requisite amount of movement being obtained by a system of multiplying levers. This also proved im-. practicable as a means for opening the valve within the required limits of temperature. The author then came to the conclusion that it was expedient to use a thermometer only to determine the temperature at which the valve was to be moved, and to rely upon some other force to operate the regulating valve. He also determined to move the incubator into his work-room and to use lamps to furnish the heat, as this course would enable him to continue his experiments while the steam boiler for heating the house was not in use.

Upon determining to use lamps, the first problem that presented itself was the regulation of the heat supplied by them. Ordinary kerosene lamps require so much force to turn the wick up and down that it seemed useless to attempt to regulate the heat in that manner. The author knew of the use of sliding wick tubes for varying the flame of the spirit lamps used in chemical laboratories, but feared that these might become so clogged by crusts or deposits from the flame that their free movement would be prevented ; he therefore gave up the idea of using them, and finally came to the conclusion that the easiest way to regulate the heat would be to permit the flame of the lamp to burn regularly as it might be set by hand ; and to either use the heat, or to let it escape without materially heating the incubator, as the heat of the incubating chamber fell or rose. In order to operate upon this system, the author invented his waste heat chimney, which in its simplest form is a chimney arranged within the ordinary chimney or flue of a lamp, and fitted at its upper end with a valve. When this valve is closed, the hot products of combustion from the lamp are compelled to pass between the central waste heat chimney and the ordinary chimney or flue ; and the walls of the latter being thereby heated transmit heat to the incubator. When, on the other hand, the damper valve is opened, the products of combustion take the direct course through the waste heat chimney and escape at its upper end, leaving the outer flue unheated. The operation of this contrivance is attended with an incidental operation which was not anticipated, but which is important. When the heat passes through the waste heat chimney, the draught is much stronger than when the heat is passing through the outer flue ; and the effect of this stronger draught is to cause the air which enters the cone or deflector of the lamp to be deflected more forcibly against the flame at the flame slot of the burner, and consequently to reduce the volume of the flame. Hence the opening of the valve or damper of the waste heat chimney not only allows the heat to waste, but also causes a reduction of the flame, so that the heat given out by the lamp is reduced ; while the closing of the valve of the waste heat chimney not only utilizes the heat, but also causes the flame to increase in volume. The two movements of the valve therefore produce incidentally effects upon the flame similar to those of lowering and raising the lamp wick.

The next matter to be decided was the means of circulating the heat through the incubator, and for this purpose water heaters were used operating upon the plan employed to heat green-houses. Two lamps were employed for heating, and a separate water heater was employed for each lamp. Each heater consisted of an endless pipe of rectangular cross-section, constructed in the form of a square ring and set on edge. A pipe or flue was soldered into one of the sides of this ring heater, so that the heated gases from the lamp might pass through this flue, and heat the water surrounding it. The water so heated rose in the upright side of the pipe heater, circulated horizontally along the upper horizontal part of the heater, descended through the opposite upright side, and passed horizontally along the lower horizontal part back to the first upright side of the heater in which the flue was situated, thus making a

IO INTRODUCTION.

continuous circulation. The two water heaters were placed edge to edge but were reversed right and left, the lamps being at opposite ends of the incubator, so that the current in one heater circulated along the upper part of the incubator from right to left, and the current in the other circulated in the opposite direction, thus equalizing the heat in the incubating chamber.

The two drawers for eggs were arranged one over the other, and slid on rails through the rectangular space within the ring pipes. A waste heat chimney was secured in each lamp flue ; and a damper valve capable of being turned edgewise or flatwise, was arranged in the upper end of each of these chimneys so that the heat from the lamp might either be permitted to waste through the chimney, or be compelled to heat the flue and the water of the heater surrounding it.

For the purpose of moving the damper valves, the author determined to use springs controlled by electro-magnets, the circuit of electricity for which should be made and broken by the action of a thermometer. The first thermometer which the author planned for the purpose was one like Six's registering thermometer, with a large upright bulb containing methyline, which moved a column of mercury. A platinum wire was soldered into the lower bend of the syphon tube so as to make a constant communication between the galvanic battery and the mercury. A second platinum wire was soldered in a downward direction into the descending branch of the tube in which the methylene expanded, the end of the wire being set at the point at which the mer-

INTRODUCTION. II

cury would be when the temperature was 98 Fahrenheit. A third platinum wire was introduced into the open ascending branch of the syphon pipe, with its lower end at the point at which the mercury would be at 105 Fahrenheit. The operation expected was that while the temperature should be between 98° and 105 , the mercury would not make electric contact with either the second or third wires, but that both of them would be surrounded by the methylene, which is a non-conductor of electricity. Consequently so long as this condition of things lasted, no electricity would be conducted from the battery, and the valves would remain at rest. When, however, the temperature should sink to 98 Fahrenheit, the mercury would make an electric connection between the first and second wires ; and when on the other hand the temperature rose to 105° Fahrenheit, the mercury would make an electrical connection between the first and third wires. Two electro-magnets were used, and also two valve engines worked by springs ; the one to open the valves, and the other to close them. Each valve engine consisted of a train of wheels like a clock movement with a clock spring to furnish the motive power, and a fly to regulate the speed ; and each operated a reciprocating pawl which moved a ratchet wheel secured to the valve shaft ; one valve engine turning the valve shaft to the right hand, to open the valves ; and the other valve engine turning the valve shaft to the left to close the valves. Each valve engine was provided^ with a detent operated by its appropriate electro-magnet, so that when the circuit to that magnet was made by the upward movement of the mercury in the corresponding arm of the thermometer syphon, the detent was operated, and the valve engine was permitted to work and to move the valves.

An electric switch was introduced into each circuit, and a connection made between the valve shaft and these two switches so that whenever one of the valve engines had worked sufficiently (to open or close the valve) the switch appertaining to the electro-magnet of that engine was opened and the electric current was broken notwithstanding the continuance of the connection made by the mercury of the thermometer. The other switch was simultaneously shut so as to make the electric circuit for the other valve engine complete except the gap to be filled by the movement of the mercury of the thermometer ; consequently whenever the mercury was moved sufficiently by the variation of temperature, the electric circuit for the valve engine was completed. The thermometer was arranged upright at the rear of the egg drawers, and the foul air was permitted to escape at the top of the incubator through a short pipe ; the escape being regulated by a damper valve that was opened and closed with the waste heat valves, so that whenever the heat within the incubator rose to 105 the draught of air through it was increased simultaneously with the shutting off of heat from the lamps.

When this apparatus was set at work with several thermometers distributed in the drawers, certain defects were speedily demonstrated. In the first place it was found that the upper drawer had an average of eight degrees higher temperature than the lower, although the difference in level did not exceed four inches. In the second place, it was found that the fresh air admitted at the bottom of the incubator did not distribute itself equably throughout it, but formed currents, taking about the shortest lines from the entry orifices to the escape orifice at the top, while eddies were apparently formed in other parts. Hence the temperature at different parts of the same drawer, and at the same level in the incubator, varied materially ; and although the difficulty was overcome to some extent by introducing perforated diaphragms beneath the drawers to distribute the air, this plan proved unsatisfactory. Another defect was the vertical arrangement of the thermometer bulb, which caused its upper end to be materially hotter than its lower end. Another difficulty arose from the fact that the methylene of the thermometer prevented an immediate electric connection between the mercury and the platinum w T ire ; hence the mercury would sometimes rise half an inch above the end of the wire in the methylene of the thermometer before the electric circuit would be completed.

These defects rendered it useless to attempt to hatch eggs with the incubator, and it was determined to reconstruct it, using the same egg drawers. To obviate the first defect, the two egg drawers were placed side by side at the same level. To obviate the second defect, a new system of ventilating an incubator was devised which has proved to be one of the essentials of success for artificial incubation, and for which, among other improvements, the author has received a patent (No. 193,616, A.D. 1877).

According to this system, the fresh air for ventilation is admitted into the incubating chamber at its top, while the air in the chamber is drawn off nearer its bottom. The warm air is thus forced to circulate downward against its natural upward tendency ; and the practical result is that local currents do not - form, and the air arranges itself in layers or strata which sink gradually and are of nearly uniform temperature at the same level throughout the incubating chamber.

A new thermometer was procured with a horizontal methylene bulb connecting with an upright inverted syphon pipe for mercury ; and a steel float swimming upon the mercury was used to communicate motion to the switches for making the electric circuits for the electro-magnets. For this purpose the float was suspended from one arm of a balance lever which it moved. This lever also carried suspended from each arm an inverted U shaped platinum wire, having its ends arranged to dip into two mercury cups connected with the circuit wires. The connection between the float and the balance lever was so adjusted that when the temperature w r as midway between the two extreme limits, the balance lever was level, and neither wire was dipped into the mercury cups ; when, however, the float was lowered by a fall of temperature, the lever tipped and one of the bent wires or switches was lowered into one pair of the mercury cups and completed the circuit of one electro-magnet, while the second switch was raised ; and when the float rose, by the rise of the temperature, the second switch was lowered to complete the circuit of the second electro-magnet, while the first switch was raised. The clock mechanism for moving the valves, and the system of breaking the circuit by the movement of the valve shaft, after the valves had been moved the proper distance by either valve engine, were used as before.

In order that the regulating thermometer might be affected by the mean temperature of the two egg drawers, the thermometer was placed in the base of the ventilating chimney for the foul air. This base was formed by the space between the slides or rails of the adjacent sides of the two draw r ers, which thus became a chamber for the thermometer. The syphon pipe for the float protruded at the front of the incubator ; and the balance beam from which the float was suspended, was supported on a column in a glass case on top of the incubator.

The fresh air for ventilation was supplied through two air pipes at each end of the incubator. One of these pipes was a simple pipe rising in the incubating chamber from an aperture in the end near the bottom of the incubating chamber to w T ithin a short distance of its top. The other pipe was passed through the water heater ; it connected at its lower end with a hole in the bottom of the incubator, and its upper end delivered the air near the top of the incubator. By this arrangement, one of the pipes at each end could be used to supply air of the temperature of the atmosphere, while the other (which passed through the water heater) supplied air which was warmed by its passage through the water heater ; and either or both ventilating pipes could be used at pleasure.

In order that moisture might be supplied, water l6 INTRODUCTION.

pans were placed beneath the egg drawers, and sponges were placed in them to furnish an evaporating surface. As, however, the circulation of the air within the incubator was to be downward, additional evaporating pans were placed above the eggs so as to supply the hottest air with moisture, which would be carried down to the eggs by the descending circulation of air. One of these upper evaporating pans was suspended over each egg drawer, and was supplied with water from a water bottle placed on top of the incubator and delivering the water to the evaporator through a small pipe ; the supply being regulated by a stopcock. Each upper evaporator was provided with an overflow pipe, so that any surplus of water dropped into the pan under the eggs. This under pan also had an overflow pipe, delivering the surplus water into a vessel under the incubator.

The first trial of this new incubator with two thermometers in each drawer, demonstrated that it would operate satisfactorily. The heat throughout both egg drawers was practically uniform, the variation in horizontal directions being less than one degree ; while the temperature could be maintained by the regulating mechanism within one degree of Fahrenheit. It was fully tested for a month with thermometers in the drawers ; then, eight fresh eggs were put into the drawers, one in each corner of each drawer, and the machine was put regularly at work. About ten days after starting, some eggs that had been set upon by hens for a week were also put into the incubator. The first chicken was hatched from one of the fresh eggs on the nineteenth day,

INTRODUCTION'. \J

and the others came before the end of the twentyfirst. After these first chickens were hatched, the drawers were progressively filled with fresh eggs, and 160 chickens and a number of ducklings were hatched that season. In fact the incubator, so far as the hatching of chickens from fresh eggs (without preliminary sitting under a hen) was concerned, was practically perfect, and experience demonstrated that it would hatch every fertile egg. Substantially the same incubator was used three seasons ; but, as the electro-magnetic mechanism was costly, and the thermometer and float mechanism were too delicate for common use, it was determined to get rid of them. Accordingly, after the first season's work was completed, a thermostat was made of strips of vulcanized India-rubber and of brass riveted together, and the change of form of the compound bars by heat was employed to operate the detent of the valve engine. The valves of the waste heat chimneys, and of the ventilating chimney, were arranged to revolve, so that a quarter of a revolution of the valve shaft would open the valves, and the next quarter of a revolution in the same direction would close them. But one valve engine was used to do all the work. A weight also was substituted for a spring in working the valve engine ; the weight being arranged as in the common Cuckoo clocks. A drawer for young chickens was placed on top of the incubator, and the warm air escaping through the ventilating chimney was permitted to pass through this drawer, the temperature of which was thus maintained at about 90° Fahrenheit.

It was deemed important that there should always be a sufficient excess of force in the driving weight of the valve engine to insure the movement of the valves even in case of an accidental increase of friction ; but as such excess of weight would tend to cause the valve engine to move with great speed, and would cause the detent arms to strike the detent with a jar, a speed controller became necessary. A fly controller, such as is used in the striking movements of clocks, requires a train of cog gearing to drive it at the requisite speed, and was therefore deemed objectionable. Hence a liquid speed controller was made by arranging a four-bladed paddle-wheel to revolve in a trough of water nearly fitting the paddles, and the paddle-wheel was mounted upon and secured to the valve shaft, so that the valve shaft could be turned by the weight no faster than the water would permit the paddles to revolve. This contrivance works almost without friction, and controls the speed admirably, preventing any jar or slam.

The water heaters, egg drawers, air supply pipes, and evaporators remained unchanged.

Upon testing the incubator fitted with the thermostat it was found that the pressure of the detent arms against the detent operated by the thermostat was sufficient to hamper the movement of the latter. To obviate this defect, the detent arms were removed from the main shaft of the valve engine, and a separate shaft was added, and was connected with the main shaft by cog-wheels, so as to make a complete revolution (in place of a quarter of a revolution) for each revolution of the main shaft. This modification reduced the pressure against the detent to only one quarter of what it had been ; but it also required the reduction of the detent arms to a single one. To make this arm operate both for opening and closing the valves, two detents were placed side by side on the rock shaft with which the thermostat was connected ; the detent arm was constructed to vibrate crosswise of its plane of revolution ; the end of the detent arm was made in the form of a T ; and a self-acting switch was placed in its plane of revolution, so that the detent arm during each revolution was moved laterally by the switch, and was caused to operate alternately upon each detent. This contrivance worked well, and the incubator with it was kept in continuous operation, hatching chickens, for four months. The switch arrangement was not however as good a contrivance as the inventor deemed desirable ; hence while the incubator was in operation he devised a new plan of valve engine, in which two detents were used ; the first or regulator detent being operated by the thermostat, and controlling the action of a light spring, while the second detent was operated by this spring, and controlled the action of the weight of the valve engine.

By this contrivance the resistance presented by the valve engine to the movement of the regulator detent by the thermostat, was reduced to the friction caused by the pressure of the light spring ; and the thermostat was relieved of the labor of operating the main or engine detent which controlled the action of the weight of the valve engine. As the light spring ran down partially at each operation, a connection was made between it and the main shaft of the valve engine, so that, whenever the latter turned to operate the valves, it wound up the light detent spring as much as the latter had run down in operating the second or engine detent. The connection between the spring and the main detent was made by means of two light cog-wheels. This new form of valve engine worked admirably, and it left nothing further to be desired in that direction. The incubator, however, still contained water heaters for circulating the heat, and the author determined to dispense with these, and to circulate the heat through the incubator by the air employed for ventilation. To accomplish this, the ascending air supply pipes were made large enough to receive within them the upright flues of the lamps ; the space between the exterior of the lamp flue and the interior of the air supply pipe being about half an inch broad all round the lamp flue. The heat, radiated into each of the two air supply pipes by the lamp flue within it, caused currents of air to set upward through them ; and this air, being heated in its upward passage, and escaping at the upper ends of the air supply pipes, distributed the heat through the incubating chamber. The lamp flue, after ascending through the air supply pipe nearly to the top of the incubating chamber, was conducted horizontally toward its centre, and was fitted with an escape pipe passing through the top of the incubator, so that a large radiating surface was provided in the top of the incubating chamber. In order to supply moisture to the large quantity of air which would pass through the incubating chamber, it was deemed inexpedient to rely upon spontaneous evaporation ; consequently an evaporating pan was applied to the head of each upright lamp flue, and provision was made to supply each evaporating pan constantly and automatically with water from a font on top of the incubator.

Upon testing the apparatus with this hot air system of heating, it was found that the heat could be maintained within the required limits as easily as with the water heaters ; but the quantity of water required for moistening the air had been overestimated, and the air became so thoroughly saturated with moisture that as it cooled, while moving downward to the level of the base of the ventilating chimney, a portion of the water was deposited upon the eggs and stopped the pores of the egg shells. Such a stoppage, if complete, is fatal to incubation; because, although the hatching of the germ under such circumstances commences and proceeds regularly for some days, death takes place sooner or later by suffocation. The excessive supply of moisture was corrected by reducing the evaporators to half their first dimensions, and then the incubator worked admirably, hatching every fertile egg up to the time of breaking the shell ; at which crisis (as is always the case with eggs from parents too closely related) a small percentage of chickens are sometimes unable to free themselves by reason of some malformation, or a wrong position of the beak ; it being occasionally the case that the head of a chicken in the egg is tucked under one leg, or that the beak is deformed so that it does not pierce the shell.

The success of the hot air system, with supplementary evaporation automatically regulated in quantity, has been so well demonstrated by constant use, that it is believed it must supersede the system of water heating ; particularly as it enables a large supply of fresh air to be circulated through the incubating chamber, without an excessive loss of heat. Consequently the author now employs this system exclusively. The descending system of ventilating the incubating chamber devised by the author, insures the heating of the upper sides of the eggs hotter than their lower sides, as is the case with eggs under a hen ; while the supply of moisture above the eggs insures the saturation of the hot air with moisture before it comes in contact with the eggs, so that they are not materially deprived of it. With the usual hot water system of distributing the heat, it is necessary to wet the eggs frequently by dipping them in warm water. The system now used by the author renders such dipping unnecessary ; while the automatic supply of water by means of fonts, operating upon the principle of the bird fountain, keeps the evaporation constant, and renders it easy to observe the quantity used. .

As to the temperature required to hatch eggs successfully, the views gathered by the author from the information published on that subject at first led him to believe that only a minute variation from a certain temperature was permissible. This temperature was stated to be 104 or 105 Fahrenheit. In order to test the correctness of this temperature, the author applied a delicate recording thermometer to the breast of a sitting hen, and found the temperature to be 106 . It was, however, manifest that the egg during hatching cannot attain this temperature, because its upper side only is next to the hen,