US2243999A - Baby incubator and the like - Google Patents

Description

June 3, 1941. c. c. cHAPPLE BABY INCUBATOR AND THE LIKE Filed March 4, 1938 4 Sheets-Shet 1 WITNESSES: INVENTOR;

Charles (J. Cha Le BY W M ATTORNEYS,

June 3, 1941. c; c. CHAPPLE BABY INCUBATOR AND THE LIKE 4 Sheet-She'et 2 Filed March 4, 1938 INVENTOR: Charles (7.0m p12,- BY W ml ATTORNEYS.

j oww c. c; CHAPPLE BABY INCUBATOR AND THE LIKE FiledIMarch 4, 1958 FIZGEW June 3, 1941.

4 Sheets-Sheet 3 WITNESSES: Q

wmd

Charles NVENTOR:

ATTORNEYS.

June 3, 1941. c. c. CHAPPLE 2,243,999 BABY INCUBATOR AND THE LIKE Filed March 4, 1938 FIG. m

' 4 Sheets-Sheet 4 ATTORNEYS.

Patented June 3, 1941 BABY INCUBATOR AND ma LIKE Charles C. Chapple, Philadelphia, Pa., assignor to The Children's Hospital of Philadelphia, Philadelphia, Pa.,' a corporation of Pennsylvania Application March 4, 1938, Serial No. 193,883

9 Claims.

My invention relates to incubators, useful for the prematurely born, or for infants that are otherwise delicate or sick, or when special care after birth is desired for any reason. The incubator may also be found useful for young or sick animals, in some cases.

An important aim of the invention is to isolate the patient in the incubator from all outside influences or infections, and to provide definite and controllable conditions in the incubator chamber, including an atmosphere of determinate characteristics, if desired, such as may be most advisable in each case. Another aim of the invention is to provide for the necessary care, exam-, inations, and treatment of the patient in the incubator,or for any other attention,-without any interruption or impairment of the favorable conditions, and without need to withdraw the patient temporarily for any purpose. Other purposes, features, and advantages of the invention will appear from the following description of one species or form of embodiment, and from the drawings. All the features and combinations shown or described are, indeed, of my invention, so far as novel.

Inasmuch as the atmosphere maintained in my incubator may sometimes include more (or less) oxygen than ordinary air, or may include carbon dioxide or other gas not appreciably present in ordinary air, or may even be.entirely artificial or synthetic, .I have hereinafter generally used the expression respiratory gas," or gas simply, to cover natural air and all modifications thereof or substitutes therefor.

In the drawings,

Fig. I is a front perspective view of one form of incubator conveniently embodying the invention, with the front wall closure swung down to open position, and with a portion of the upper wall and roof structure broken out.

Fig. II is a rear perspective view of the incubator, with parts ofthe rear wall broken away or removed. 4 V Fig. III is a partial rear perspective view illustrating the use of certain features of the invention by a physician, as for examining a baby in the incubator.

Fig. IV is a fragmentary sectional view showing an armlet or sleeve device attached to the incubator around an arm-port in its wall, but rolled. up and secured or stowed as when not in use; Fig. V is a similar view with the armlet or sleeve device unrolled as for use, the ends of the sleeve being partly broken away and in section; and Fig. VI is a fragmentary view, partly sectional, showing how a hand is initially inserted in the end of the sleeve.

Fig. VII is a somewhat diagrammatic sectional view of the incubator chamber, equipped with a cooling arrangement for hot weather.

Fig. VIII is a perspective and sectional view of certainapparatus for maintaining the desired atmospheric conditions in the incubator, the view being from the left of Fig. 11. a

Fig. IX is a. wiring diagram illustrating the automatic control and regulation of the atmosphere in the incubator.

In Figs, I and.II, the incubator chamber Ill is shown as a top compartment in a. cabinet structure H, which also has a lower shelf orv bottom compartment II for accessory equipment. The incubator compartment III is completely enclosed, and all its walls (including top or roof I3 and bottom It) may be thoroughly thermo-insulated: this is suggestlvely indicated in Fig. II by a thermoinsulative layer l5 included in the wall thickness. between inner and outer wall shells it and II, which may be of metal or other suitable material. The equipment shelf or compartment i2 is also shown as enclosed and completely separate from the incubator compartment i0, though without any attempt at thermoinsulation.

As shown in Fig. I, the entire front of the incubator chamber I0 is formed by a bottom-edgehinged door l8, which has a lateral gasket l9 to make a tight joint against arabbetted seat 20 in the edges of the walls, and is provided with swing-fasteners 2| for engaging in sockets 22 in the walls, behind the seat 20. In Fig. I, the

door I8 is shown swung down to open position,

affording free access for cleaning, sterilizing, or other purposes, as well as a free view of the interior; and in Fig. II, the rear wall panel of the compartment I 0 has been omitted from its frame 23 (which is removably secured by screws or bolts 24), and the rear wall of the compartment I2, has been largely broken away. to reveal the interiors of compartments II and I2. Actually, however, the incubator chamber I! can be kept entirely closed when in use. This is made possible not only by special respiratory provisions, but also by the equipment of the incubator chamber l0, including special provisions for the her NIL-which would interrupt or impair the favorable conditions, and expose the patient to infections or drafts.

As shown in Figs. I and II, the equipment in the incubator chamber I includes a. metalbasket baby-bed 25, with mattress 26, preferably at the front of the chamber. There are also precision baby-scales 21, preferably at the rear of the chamber l0, and elevated above the bed 25, as on a pedestal 28, Figs. I, II, III and VII, the pan of the scales 21 may serve as an alternative rest for the baby, in lieu of the bed 25, as when the latter is being changed. A thermometer 29 is shown mounted on the rear rail of th bed 25, where it will give porarily not in actual use; and on the opposite so to speak, in the armports 35, 35,-or otherwise wall, higher above the bed, there is a bracket 32 for holding a gavage funnel while liquid is administered to the patient therewith. Preferably the shelf 3| and bracket 32 are removable.

roof 13 of the incubator chamber I0, directly over the bed and the devices 3|, 32, to'givea clear view of the whole interior of the chamber, It is preferably set on a slope of some or less, and may have double panes of uninfiamo mable, shatter-proof character, suitably spaced for thermo-insulation. For illuminating the interior of the chamber I0, an incandescent electric lamp 34 may be conveniently placed therein,

as in an upper rear corner, with suitable screen- 35 ing to prevent glare in the patients eyes.

'I'o permit necessary access to the interior of the incubator chamber Ill without opening it, it has wall openings or armports 35, 35, preferably in its front wall 18, with provisions to prevent influx 'or 40 efiiux of air or gas when the hands (and arms) of an attendant are inserted through them. For this purpose, flexible tubular armlets or " sleeves 36, 36 of gasproof fabric (e. g., balloon cloth) are attached to the wall l8 around the openings 35, 35, as shown in Figs. I, II, III, IV and V. ,As shown in Fig. IV, each sleeve 36 has a hoop 311 sewn into the hem at one (larger) end, which lies in a groove in a clamping ring 38 that is secured to the inner side of the wall ID by screws 39. In the wristband hem at the other (smaller) end of the sleeve 36 is enclosed a very extensible elasticirubber) band 40, which gathers or puckers the wristband fabric'together and closes the opening when the sleeve is not in use, This contractile free end of the sleeve 36 fits around an attendants arm above the hand, and the length of the sleeve permits the hand and arm to be introduced into the incubator chamber and moved around therein freely,,as hereinafter de- 0 scribed.

When an attendant wishes to use one of the sleeves 36, its elastic l readily allows the wristband to expand .for insertion of a hand, as

shown in Fig. VI. The hand being thus inserted 5 out as it follows the hand through the armport 35, allowing insertion of the arm into the chamber ID to any extent desired. The flexibility and length of the sleeves 36,36 allows the attendant to move his hands and arms about freely in the incubator chamber ID, to do whatever i needed As is apparent from 10 An observation window 33 is provided in the top or 25 to or for the patient, as indicated in Fig. III, while all the time observing everything in the chamber as he stands in front of it, looking down through the window 33. If the attendant wishes, he can readily slip his hands under a. baby lying on the bed 25 in Fig. III, lift him upward and rearward, and place him on the scales 21 and weigh him, and afterward return him to the bed again,the range and freedom of movement allowed by the sleeves 36, 36 being ample for this.

When the attendant has done everything desired, he merely draws his arms out through the openings 35, 35 and steps back away from the incubator, thus drawing out and reversing the sleeves 36, 35 through the openings 35, 35 and finally withdrawing his hands through the wristbands,when their ends are at once automatically closed by the elastics 40, 40, as shown in Fig. V. Then the sleeves 36, 36 may be twisted /2 turn, rolled up, and tucked into themselves,

tend into the chamber 10, preferably in its upper portion at one end, above the'bed 25 and the scales 21, As shown in Figs. I and II,- the inner lock door 34 forms the front lock wall and is hinged to swing open horizontally, against the end wall of the chamber I0, while the outer door is in the top or roof of the air-lock 42 and of the chamber Land is hinged to swing open upward and rearward, Fig. II. Internally, the

bottom of the lock-chamber 42 is shown stepped,

affording convenient places for anumber of tall milk bottles, and for shorter articles. With the lock 32 in the location shown, its inner door 44 and its interior are readily accessible to an at-- tendants hand when inserted through one of the sleeves 36, as he stands in front of the incubator in Fig. III; and the outer lock door 45 is also within easy reach'oi' his (other) hand, Moreover, the lock chamber 42 serves as a screen or shield to keep the light 34 from shining in the patients eyes. Very small articles can either be passed in and out through the lock 42, Or introduced and withdrawn in the hand, through one of the sleeves 35.

As shown in Figs. III and VII, an apertured plug-in fitting is provided in the top or roof of the incubator chamber l0, consisting of an elastic vulcanized rubber stopper 4'! with a hole through it. This device allows tubular connections to be made therethrough from the baby to a point outside the chamber roof, adjacent the attendants head as he stands at the window 33.

For this purpose, one or more metal or other tubes 48 may be inserted in the rubber stopper 41, from the inside or the outside, or both, and rubber tubing may be attached thereto inside the chamber I0, and also outside if required. By means of such tubular connections, many operations can be conveniently eifected,such as administration of emergency oxygen and carbon dioxide, aspiration, or stethoscopic examination as shown in Fig. III, etc. Asis apparent from Fig.

III, such tubular connections, do not interfere 7 2,248,999 with the attendants view through the window asas he stands with hishand (s) inserted through the sleeve (s) 36.

Complete isolation of the patient in the closed incubator chamber In is in itself a very helpful protection againstinfection, as well as against- The operation of the heater 49 may be automati cally controlled and regulated by a thermostatic device located at a suitable point in the chamber 19, so as-to respond to the atmospheric temperature affecting the patient. As shown in Figs. I and II, the thermostat 5| is mounted on the end wall of the chamber l6 beneath the air lock 42, but well above the bed 25, alongside a protective foraminous metal grillage '5! sur-- rounding the open discharge end of the air supply conduit 59 and the air heater 49,said heater 49 being in this instance located within the chamber 19 itself, and wound on or around the upper end of the conduit 59. The thermostat 5| and the heater 49 serve to maintain a substantially constant and uniform temperature in the incubator chamber l0, regardless of outside vari ations.

temperature desired from time to time.

In the case of the prematurely born, fairly high temperatures are desirable for the air breathed, as well as for the general environment: e. g., some 85-90 F., for example. The isolation of the incubator chamber II and the effective control and uniformity of the temperature therein afford the further advantage that clothing can be gradually reduced, and even discarded altogether after a baby has become accustomed to the incubator: e. g., a shirt and diaper are quite suflicient clothing. This not only simplifies the care of the baby withoutopening the incubator, and facilitates examining him in any and every way, but allows him freedom of exercise, as well as skin ventilation.

Besides temperature, another condition or Located as shown, the thermostat 5| is easily reached through one of the sleeves 35, for the purpose of setting it to maintain the exact ings of the pipes 50, 54) downward (about 2 ft.)

characteristic of incubator atmosphere which it is highly desirable to control and regulate-is the humidity; and as the most advantageous way of doing this, I provide for humidii'ying the air or respiratory gas supplied to thechamber ll, preferably under the automatic control of a humidostatic device 53 suitably located in the chamber to respond to the humidity there. As

mounted on the end wall of the chamber ll adiacent the thermostat 6|, well above the bed 26. It is also desirable to purify the respiratory gas As shown in Fig. II, the gas supply pipe 50 already mentioned extends from the incubator chamber l0 downinto the lower compartment II, where the treating and circulating equipment of the system is located, as well as some of the control provisions. For withdrawing the air or gas from the chamber l0, an outlet or return conduit 54 extends from the chamber l0 down into the compartment l2. The return conduit 54 may be at the same end of chamber I'll as the supply conduit 50, but its opening is preferably at a lower level than that of conduit 50, though higher than bed 25. The air or gas supplied through conduit 69 rises through the heater 49 at once to the top of the chamber l6 and flows to the other end thereof, where it descends and returns to conduit 54, by reason of the suction therethrough, all as shown by the arrows in Fig. II. Some silk threads 55 hanging in the upper left hand corner of chamber Ill, over supply pipe 50, show when the circulation is working properly. Thus the circulation in the chamber I0 is substantially or mainly confined to its upper portion, above the bed 25, leaving the patient on the bed out of the principal path of air flow. As shown, the open upper end of conduit 54 is cut oil diagonally, to minimize the possibility ofblockage by accidental coverage of thesame. At the opposite end of the chamber l0, preferably, from the supply and outlet conduits 50, 54, there is a Pressure-relieving air or gas vent pipe 55, extending from the chamber bottom l4 (below the openthrough the compartment I2 and beneath the floor of the latter, where its end is open. A foraminous tubular hood or screen 56 is shown over the open upper end of this pipe 55, to prevent dirt or lint from getting into it and clogging it up. The temperature in the closed chamber In makes inflow of air through pipe 55 impossible, being normally higher than the outside temperature. The fact that the vent pipe 55 opens from the chamber bottom below the path of circulation therein assures gradual removal and replacement of the stagnant air in the bottom of the chamber.

The circulating and conditioning equipment in compartment 12 includes (Figs. II and VIII) a receiving, mixing, and filtering chamber in a casing 66; a (centrifugal) blower 6|, directly driven by an (electric) motor 62, and preferably of a silent type; and a humidifier in a tank or shown in Figs. I and II, the humldostat 59 is casing 63, which may serve to wash the air or respiratory gas more or less. ,Into one end of the chamber 69 are connected the return condult 54 from the incubator chamber l9 and a valved supply fitting 64, serving forthe attach ment of a flexible hose leading out of doors, or to any suitable source of pure, fresh air. Another valved supply fitting 66 is shown connected into the same end of the chamber 60,for

' the attachment of a hose connection (not shown) supplied to the chamber II by filtering or other means, so as to exclude dust and dirt from the chamber. To facilitate the humidifying, heating pensatively venting air or gas from the system,

to relieve the pressure that would otherwise tend tobuild up in the chamber ll.

admitting oxygen or other respiratory gas which it may be desired to mix with that returning through the conduit 54. Into the opposite end of the chamber 60 is connected the (axial) intake of the (centrifugal) blower 6|, whose (peripheral) discharge delivers into the upper part of the closed casing or tank of the humidifier 63 at one end. A valve-cock 68 is shown on the blower casing, for taking samples ofthe incubator atmospherefor test or analysis. At an intermediate point between the connections 54, 64', and 66 and the blower 6|, one or more air or gas filtering diaphragms 69 extend entirely across the interior of the chamber 60. As indicated in Fig. VIII, one side III of the chamber or casing 60 is readily removable, to allow inspection or renewal of the filters 69.

As shown in Fig. VIII, a valved exhaust line H (leading out of doors) may be-connected to the return conduit 54, with suitable dampers or valves, to allow of exhausting the gas from the chamber In, instead of recirculating it.

As shown in Figs. II and VIII, the air or gas supply conduit 50 isconnected into the upper portion of the humidifier tank 63 at the opposite end from the blower 6|, so that the air or gas from the blower passes through the tank from end to end, in contact with the body of water in its lower portion. If desired, one or more baflles l2, -'l2 may extend down from the tank top close to the surface of the water,'and may even dip into the water, if its level is higher than shown in Fig. III,--to compel intimate contact of the air or gas with the water, so as to be cleansed or washed thereby. Immersed in the water in the humidifier tank 53 is shown an (electric) heater [3 for heating and vaporizing the water,and even boiling it vigorously, if need be,so as to humidify the air to any degree desired, up to complete saturation. Obviously, the control and regulation of this heater 13 by the humidostat 53 will determine the percentage humidity in the chamber lii.

To assure a substantially constant'surface exposure of water to the air in the humidifier 63, it suffices to maintain a substantially constant amountand level of the water. As one way of doing this, water may be supplied to the humidifier tank through a pipe connection 15 from a supply apparatus 16 (resembling a common form of water cooler) comprising a vessel in whose open top sits an inverted bottle 11, so that the level in the tank corresponds to the vertical position of the bottle-mouth. Distilled or boiled water is to be preferred for the humidifier 63.

As shown in Fig. II, the compartment I2 contains a control-panel 18 carrying various electrical parts and mechanisms, hereinafter set forth. There is also an electric lam'p 19 mounted on the floor of the compartment l2, in position to facilitate inspection of the water supply at H, the control-panel I8, or the filter 63, as well as the making of hose connections to the fittings 64, 66, or the adjustment of their valves to regulate the supplies of air or gas through them. v

In hot weather, cooling rather than heating may be required to maintain desired living temperatures of the respiratory-gas in the incubator chamber Hi. This may be effected anywhere in the circulatory system of the incubator; and one simple way is to do it in the chamber Ill itself. For this purpose, Fig. VII shows the chamber ID with its usual (thermoinsulative) rear wall panel and its frame 23 removed, and replaced by a cooling wall 301 attached to the incubator by the screws 24 that usually serve to secure the panel frame. As shown, this wall 80 comprises a (thermo-insulated) metal tank with a hinged lid 82, which may contain any suitable cooling medium, such as a body of water, brine, or other liquid, itself kept cool (for example) by pieces 83 of ordinary ice (or dry ice) immersed in the liquid. The cooling effect may be augmented by providing the cooling wall 80 with heat-absorbing means projecting into the chamber Iii, such for example as metal tubes 85 having their upper and lower ends secured in the tank wall, so that the cooling liquid in the tank may circulate through them.

Whatever its character and'arrangement, the cooling means employed should, of course, be capable of cooling-the respiratory gas sufficiently to maintain the desired living temperature in the chamber l0 under all c0nditions,even

.when the external temperature reaches the extreme possible limit of excess. When this is thecase, variations of the excessive external temperature will always be compensated for automatically by the heater 49 and the thermostat 5|: e. g., if the wall tends to overcooi the atmosphere in the chamber In, the heater 49 will operate enough to maintain the desired constant temperature there, notwithstanding any variations of the excessive external temperature-just as if the entire surroundings of the incubator were over-cool, rather than overhot.

Fig. IX illustrates one suitable scheme of electrical connections for the incubator, whose main operating electric circuit 99 may be supplied with current (through a flexible cord, not shown) from any suitable A. C. or D. C. source,- such as an.ordinary 110-120 volt house lighting circuit (not shown).

As shown in Fig. IX, the main operating circuit is connected to the aforesaid flexible cord (not shown) through a normally closed control switch 9|, located in any convenient position on the incubator cabinet Directly across the main incubator circuit 90 are connected the lamps 34 and i9 and the motor 62 that drives the blower 5| so that circulation of respiratory gas through the incubator chamber I0 is assured whenever current is on, and any failure of current supply is obvious at a glance. In parallel across the main circuit 90 are connected supply circuits 92, 93, for the respiratory gas heater 49 and the humidifier water heater 13, controlled by thermostat 5| and humidostat 53, respectively. As shown, the circuits 92, 93'include relay switches 94, 95 which close when their operating coils are energized from control circuits 96, 91 that are connected across the supply circuits 92, 93, and include thermostat 5| and humidostat 53, besides current-limiting resistances 98, 99. Thermostat 5| and humidostat 53 maybe of any commercial types that will open the circuits 96, 91 when the temperature and humidity rise to the limits for which they are set, and vice-versa. By reaching through a sleeve 35, they may be set and reset to maintain any temperature and percentage humidity that may be desired from time to time, within a range of deviation not exceeding 1' F. and 5% of saturation.

As a protection against any possible failure of the switches 94, 95 to open when required, or

against excessive temperature in the incubator chamber l0 arising from any cause, a safety thermostatic device Hill is shown in Figs.- I and II, (and IX), inounted'on the end wall of the chamber between thermostat 5| and humidostat mostat I99 is itself in a control circuit )2 connected across the main circuit 90 and including the operating coil of relay switch llll, as well as a current-limiting resistance I03. An alarmcircuit I04 is shown connected across the main circuit 90, and including an audible alarm bell I05 and a (red) light I 06-connected in parallel therein, as well as contact l0! arranged to be closed by the relay switch llll when it drops open, and a control switch I08 of its own. The safety thermostat I00 may be of any commercial type that operates to openits circuit I02 when the temperature-rises to the limit for which it is set, and (preferably) requires to be manually closed after each operation. Or, if preferred, the relay switch IDI may be such as to require manual resetting aiter each operation.

' The dot-and-dash outline of the control panel 18 in Fig. IX includes those features of the electrical system which may ordinarily be mounted on this panel in practice.

The use and operation of the incubator and its circulating and conditioning system will for the most part be apparent from what'has already been said. Aided by cooling from a wall tank 80 in hot weather, the system is capable of automatically maintaining in the chamber iii an atmosphere whose essential characteristics of temperature and humidity are definitely determined and kept constant-,-its purity being assured by filtering and by admixture of outside The fresh air or the recirculated air (or both) may be exposed to ultra-violet light to sterilize the air completely. The exact composition of the incubator atmosphere can be con-' trolled as desired by supplying oxygen or other" gas at 66 and by suitably adjusting the valves at 64, 66. If desired, valve 64 can be closed, and the whole system (including chamber Ill) may be charged and operated exclusively with special mixtures of gases, supplied for replenishment at 66. Or, by closing both the valves at 64, 56, the gas in the system may be recirculated indefinitely, without substantial addition or loss. Under these circumstances, chemicals for absorbing carbon dioxide, odors, or excess water vapor may be introduced into the circulatory system where most convenient.

Having thus described my invention, Iclaim:

1. The combination of a closed incubator chamber, with a transparent window at its front, for containing an atmosphere of respiratory gas of determinate characteristics, to be breathed bya patient in the chamber; a rest and weighing scales for the patient in the lower part of the chamber, beneath said window; and flexible sleeves attached to the front chamber wall around arm openings therein and permitting an attendant to insert his hands into the chamber and said sleeve, and including means for excluding from the lock the respiratory gas and the outside air.

3. In an incubator of the character -described, the combination of a closed incubator chamber, with a transparent window at its front, for containing an atmosphere of respiratory gas of determinate characteristics to be breathed by an infant in the chamber; flexible sleeves attached to the front chamber wall around arm openings therein and permitting an attendant to insert his hands into the chamber and move them around therein; and an air lock for passing articles into and out of theincubator chamber comprising a lock chamber in one end of the incubator chamber, accessible to an attendants hand inserted into the incubator chamber through one of said sleeves, with an inside closure for excluding respiratory gas from the lock chamber, and an outside closure for excluding outside air therefrom located within reach of a hand of the attendant while observing the infant through the window and reaching the air lock witl. his other hand inserted through one of said sleeves.

4. In an incubator of the character described, the combination of a closed incubator chamber, with a transparent window at its front, for containing an atmosphere of respiratory gas of determinate characteristics to be breathed by an infant in the chamber; a bed in the lower front part of the chamber, beneath said window; weighing scalesin the chamber, behind said bed; and flexible sleeves attached to the front chamber wall around arm openings therein and permitting an attendant to insert his hands into the chamber and move them around therein, so as to attend to an infant on the bed while observing him through the window, and to shift the infant from the bed to the scales and weigh him on the latter, all without substantial influx or escape of air or gas.

5. In an incubator of the character described, the combination of a. closed incubator chamber, for containing therein an atmosphere of respiratory gas of determinate characteristics to be for excluding the respiratory gas from the lock move them around therein, so as to attend to a patient on the bed while observing him through the window, and to weigh him on the scales, all

around an arm opening therein for permitting the hand and arm of an attendant to be inserted into the incubator chamber and moved about therein without material influx or escape of air or gas; and an air lock for passing articles into the incubator chamber into reach of the attendant's hand inserted into the chamber through chamber and a closure for excluding therefrom the outside air.

6. In an incubator of the character described,

the combination of a closed incubator chamber,

and means for circulating respiratory gas therethrough; a humidifier and a heater for-the gas thus supplied to said chamber, both including means whereby heat is supplied to the gas; an electric circuit ior supplyingenerg'y to activate said circulating means, said humidifier, and said gas heater;. means responsive to the humidity and the temperature in said chamber for controlling the activation 01' said humidifier and said gas heater from said electric circuit, without affecting that of said circulating means; and

means independently responsive to excessive temperature in said chamber for cutting 011 both said humidifier and said gas heater from said circuit, while leaving said circulating means connected thereto.

7. In an incubator of the character described, the combination of a closed incubator chamber, and means for circulating respiratory gas-therethrough; a, humidifier for the gas thus supplied to said chamber, with means for heating and vaporizing water therefor; a heater for heating said gas; means responsive to the humidity and temperature in said chamber for controlling the heating of the water and the gas, respectively, by the corresponding means aforesaid, without afiectlng the operation of said gas circulating means; and means independently responsive to excessive temperature in said chamber for rendering both said water heating means and said gas heater inactive, also without affecting the operation of said gas circulating means.

8. An incubator oi the character described comprising a unitaryupright cabinet with an impermeable dividing floor defining in the cabinet a substantially closed upper incubator compartment and a separate lower machinery compartment; 9. bed on said floor, in the lower portion of said upper compartment; conditioning means in said lower compartment, including a gas-humidifier; a gas-supply conduit extending from said lower compartment up into said upper compartment, and discharging in its upper portion, substantially above a patient on the bed, and a return conduit drawing from a level in said upper compartment substantially above a patient on the bed and extending down into said lower compartment, so that the patient on the bed is left clear of any draft due to the circulation, and mechanical air circulating means in said lower compartment, beneath said floor, for drawing respiratory gas from said incubator compartment down through said return conduit and passing it through said humidifier and back through said gas-supply conduit into said incubator chamber.

9. In an incubator of the character described,

1 the combination of an incubator chamber:

therein, even when the external temperature is excessive; so that by the cooperation of said heating and regulating means with said cooling means, a substantially constant desired temperature and humidity may be maintained in the chamber, notwithstanding variations of the excessive external temperature.

I CHARLES C. CHAPPLE.

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