Патент USA US2131554код для вставки
Sept' 27, 1933- J. DEv RAYVILLÈ HYGROMETER 2,131,554 ‘ Filed Feb. l, 1936 »ma ATTORNEYS Patented Sept. 27, 1938 2,131,554 UNITED STATES PATENT OFFICE 2,131,554 HYGROMETER Jean De Rayville, New York, N. Y. Application February 1, 1936, Serial No. 61,936 13 Claims. The invention relates to hygrometers. ' One of the objects of this invention is to pro vide a simple, practical and dependable device for indicating, or responding to, the factor of humid 5_ ity of an atmosphere. Another object is to pro vide a hygrometer construction that will be simple and inexpensive to manufacture, capable of ease and rapidity of assembly‘and capable of being quickly and easily set or adjusted. Another 10. object is to provide a construction ofthe above mentioned character in which acceptable accu racy of indication or response to the humidity factor of an atmosphere may be achieved without requiring high or expensive degree of precision 15. in manufacture. Another object is to provide an instrument of the above-mentioned character which will be substantially self-adjusting under certain conditions liable to be met with in prac tice. Another object is to provide an instrument 20 of the above-mentioned character in which the various degrees of humidity to which it is re sponsive may be conveniently and easily indi cated visually. Another object is to provide an instrument of the above-mentioned character 25 which in general will be well adapted for inex pensive and quantity production in which vari ous parts may be easily and inexpensively manu facture-d and assembled and which will also have the features of adequate strength and durability 30 of construction and of adequate reliability of ac tion. Other objects will be in part obvious or in part pointed out hereinafter. The invention accordingly consists in the fea tures of construction, combinations of elements, and arrangements of parts as will be exemplified in the structure to be ’hereinafter described and the scope of the application of which will be indi cated in the following claims. ' In the accompanying drawing in which is 40 shown one of the various possible embodiments of my invention Figure 1 is a front elevation of the instrument on a small scale, certain parts being broken away; 45 Figure 2 is a front elevation as seen with the front or cover and certain other parts removed, thereby to show certain interior parts more clearly; _ » Figure 3 is a sectional view as seen substan 5 tiallyalong the line 3-3 of Figure 1, the plane of ' the section being also indicated at 3-3 of Figure 2 in order thereby better to correlate these three figures, certain parts of Figure 3, however, being shown in elevation; 5,5 Figure 4 is a fragmentary perspective view (Cl. 73-337) showing thel construction of certain elements of the instrument structure; Figure 5 is a sectional view -as seen along the line 5-5 of Figure 3, and , ' ` l ‘ Figure 6 is a fragmentary'detached view show ing the construction of the sliding connection be tween certain of the parts. ` Similar reference characters'refer tov similar parts throughout the‘several views in the draw mg. > ` 10 Referring now tothe drawing and more par ticularly to Figures 1 and 3, the instrument has a suitable enclosure which is preferably cylindrical in shape and preferably comprises a casing gen erally indicated at I0 (Figure 3), the casing hav 15 ing cylindrical walls II closed at one end by an end wall l2, the casing I 0 being preferably of sheet metal and hence lending itself readily to drawing or stamping into the desired shape; the end wall I2 would appear as the rear wall (not shown) in Figure 1. The cylindrical side wall Il` has secured to it a suitable standard or base I3 (Figure 1) by means of which the instrument may be> stood up as on any suitable horizontal supporting surface, such as a table, shelf, or the like, though, of course, any other suitable means may be employed for mounting or supporting the ultimate instrument where and in any manner desired. The forward portions of the cylindrical side 30 walls II, appearing as the upper portions in Fig ure 3, are stepped or flanged as at I4 in order telescopically to seat thereabout the cylindrical ~ side flange I5 of the casing cover generally in dicated at I6, the latter having a disk-like front face I'I forming, in effect, the front end wall of the enclosure Ill-I6. The cover I6 is also pref erably made of sheet metal and may be easily stampedy or `drawn into the form described. .The enclosure portions I0 and I6 are preferably detachably connected and, moreover, and pref erably, in a mannerV to permit a certain amount of rotary adjustment or movement therebetween; for this purpose two or more bayonet joints indi cated at I8 and I9 in Figure 1 may be employed, the respective parts of which being related to the flanges I4 and I5 in any suitable or known man ner. Thereby assembly or disassembly of the enclosure portions I0 and I6 may easily be had while the pin and slot connections of the bayonet joints are made of such lengths, as will later be seen, as to permit the cover I6 to be manually adjusted or rotated relative to the casing I0, all for a purpose also later described. At preferably the center of the disk-like rear 55 2,131,554 2 or end wall I2 (Figure 3) there is secured rigidly but preferably detachably a post 20, preferably of metal, and, as is better shown in Figure 5, the post 20 is provided with two diametrically op posed longitudinally extending slots 2| and 22. Into these slots are received the moisture- or humidity-responsive elements 23 and 24, respec tively, being secured to the post 20 in any suit able manner as, for example, by wedging them into the slots or by clamping them therein, such action being achievable by pressing the opposed walls of the slots toward each other. As will later be seen, numerous features of my invention can be carried out by the use of only one of the elements 23, 24 but because, due to certain otherfr features of my invention, I am enabled to bring into action forces acting by way of a mechanical couple, I therefore prefer to employ, and hence I show in my preferred embodiment, two mois 20 ture-responsive or hygroscopic elements 23--24. The latter elements are preferably each made of two coacting members differently responsive to changes in humidity, and in Figure 4 I have shown in fragmentary perspective a possible mode 25 of construction of these elements. The elements are sheet-like in form or shape and each com prises two sheet members A and B secured to gether, face to face, as shown in Figure 4. For example, one sheet member, such as member A, may be of a relatively thin sheet of wood, the sheet being cut lengthwise of the grain and illus tratively being of a thickness on the order of 0.01 inch. The wood employed may be any suitable wood that is suitably hygroscopic and initially is, for assembly purposes, treated to be substantially dry. The other element B may comprise any suitable bendable or flexible material that is non hygroscopic; it may, for example, be waterproofed paper and the two members A-B are secured together face to face by any suitable adhesive that is non-hygroscopic. Preferably the material of element B has a temperature coeflicient of ex pansion, as compared to that of the element A, that temperature changes have no or a negligible effectV on the action of the combined elements. The member B, however, may also be of wood and in such case it is cut preferably >thinner than member A, being of a thickness on the order of 0.001 inch, as compared to the above-described thickness of the wood member A, and being in such case a sheet of wood cut, however, length wise of the grain, the two members A-B being secured together back to back as above described. Any suitable adhesive may be employed that is substantially non-hygroscopic, such as rubber cements, celluloid or cellulose cement composi tions, adhesives such as are used in so-called “dry mounting” work, and the like. Where both members A and B are of wood, I prefer to employ holly wood. In any case, the parts A and B are secured together, preferably under pressure,'but in such condition that they are free from mois ture content and hence preferably oven dry. The elements 23 and 24 are so related to the stationary cr ñxed post 20 that the grain of mem ber A of each element runs in a direction parallel to the axis of the post 20, that axis being, as will later be clear, the axis about which the elements 23 and 24 curve or bend or flex lunder the effects 75 of the moisture inthe atmosphere. In Figure 3 the direction of the grain of member A of'element 24, is clearly shown, as just. described. Where member B of these elements is made of wood, it is so related to the member A that its grain extends in the direction of a radius ema nating from the axis of the post 20, it being thus clear that the grains of members A and B of each of the elements 23, 24 extend transversely of each other. Thus, the .grain of member B of element 23 is shown in Figure 3 as extending radially and that direction of grain is true also of the member B in back of the member A of element 24. With this arrangement and construction of the elements 23, 24, the latter bend or warp or ñex or curve about the axis of the post 20, thus giving the 10 outer ends of the members 23, 24 a motion of ` translation along a curved path. This motion of translation is communicated in ampliñed form to certain indicating means to which reference might first be made before describing the manner 15 and means in which such motion is transmitted. Accordingly, and referring again to Figure 3, the face or end wall .I1 of the cover I6 carries an inwardly directed stud 21, secured thereto in any suitable manner and substantially at its center, 20 the axis of the stud 21 and the axis of the post 2U being in alinement or coincident, the stud 21 hav ing a head 28. The stud 21 serves as a shaft for a bushing 29 to which is secured an elongated sheet metal cross-member generally indicated at 25 30, member 30 being thus rotatably mounted by bushing 29 upon the stud 21, its length, as is better shown in Figure 3, being slightly less than the inside diameter of the enclosure lli-I6 so that it may freely rotate within the enclosure. Its two arms, each to one side of the hub or bushing 29, are provided with radially extending slots 3|, 32, as is better shown in Figure 2, for a purpose later to be set forth. Resting upon the cross-member 30, as viewed in _Figure 3, and thus positioned in front of the later, as viewed in Figure 2, is a disk-like dial 33 of a diameter of less than that of the enclosure Ill-I6 (see Figure 3) and made of any suitable light sheet material, such as light sheet metal, 40 suitable cardboard, celluloid, or the like, and it is apertured at its center so as to be received upon the bushing or hub 29l (Figure 3) relatively loosely; the dial 33 may thus be easily given a rotary movement relative to the hub or bushing 45 29 and hence relative to the cross-member 30. The dial 33 is to be rotated or driven in re sponse to rotary movement of the cross-member 30 and the driving connection between these two members is preferably a friction clutch type of connection constructed in any suitable manner to cause the cross-member 30 to swing or rotate the dial 33 but to slip or yield when the load becomes greater than that represented by the dial disk 33 alone, for a purpose later described. A suitable and illustrative driving connection of this type may comprise spring-like tongues 34 and 35 (Fig ures 1 and 3) attached to or integrally formed with the cross-member 30, ythe two tongues ex tending upwardly fromV the plane of the cross 60 member 30, as viewed in Figure 3, and being bent into overlapping relation with respect to the dial 33, the springiness of the tongues being so ad justed that the corresponding diametrically op posed peripheral portions of the dial are gripped between the tongues and the cross-member 30, frictionally, so that the `dial 33 has to follow the rotary movements of the cross-member 30; how ever, if the dial 33 is physically halted or stopped. the cross-member 30 may continue to rotate but 70 now relative to the halted disk 33, the tongues 34-'35 permitting slippage to take place. The dial 33 is provided with graduations throughout a suitable portion of its periphery, as shown in Figure 1, graduated from 0 to 100, 15' 2,131,554 3. representing the possible range of humidity vari ations of the atmosphere, the numerical gradua tioned >therealong and to the same relative posi tions representing percentage relative-humidity Accordingly, as the elements v23, 24 bend or flex or warp in response to, for example, an Jin crease in the moisture content in the atmosphere, the enclosure Ill-16 having suitable openings 41 or moisture content of the atmosphere. If de sired, the central portions of the dial 33 may be cut out, as indicated in Figure 1, to decrease the weight of the dial, giving it a spoked' effect, as` shown. The range of graauations from 0 to 100% on 10 the dial 33 is, moreover, and preferably, divided into three areas or arcs, each of suitable extent and of a distinctive color. Thus, in Figure 1, the arcuate range C from 0 to about 40 may be colored red; the arcuate range D from about 40 to 60 may be colored white; and the arcuate range E from 60 to 100 may be colored blue. ’ These colored ranges and the graduations are made visible through the front wall I1 of the cover I6 by means of a window 36 (Figure 1) of suit able radial and arcuate extent and, `furthermore, the front wall l1 carries two arrow heads 31, 38 pointed toward each other and alined along a radius and exposed through the aperture 36, as shown in Figure l, the aperture 36 being closed by a suitable transparent member 38 which Amay be of glass, mica, celluloid, or the like. As the dial 33 is thus rotated in back of the front wall I1 or is brought to a stop corresponding to the reaction of the elements 23, 24fto the mois 30 ture content of the atmosphere, the specific per centage indication on the dial may be read oiî or seen as indicated by the arrow heads 31-38 while, for more distant observation, the color of the particular range of the lranges C, D and E (Figure 2) is visible through the aperture 36` to give a general indication as to whether the hu midity is subnormal, normal or abnormal. Recurring now to the driving connection be tween the elements 23, 24 and the dial 33, refer 40 ence may now be made to >Figures 2 and 3 from which it will be seen that there are attached to the free ends of the elements 23 and 24 levers 43 and 44. These levers are made of any suitable light material, such as light or thin sheet metal, and are in general arcuate, as viewed in Figure 2, having an arcuate extent of roughly 90°. 'I‘hey are rigidly attached to the freeends of the ele ments 23, 24 preferably by means of U-shaped sheet metal portions 45 and 45, respectively (Fig ures 3 and 5), the latter being of sufficient strength or thickness so that their flanges can be pressed inwardly toward each other and thus de pendably and securely clamp the respective ele ments therebetween, the levers 43 and 44 being rigidly secured thereto at their upper ends, as viewed in Figure 3. The otherwise free or `unanchored ends of the arcuate levers 43, 44 are provided with normally radially extending extensions 43a and 44a, respec 60 tively, substantially as shown in Figure 2, where the parts are all seen in their interrelations when the elements 23, 24 are still dry or correspond to a dry atmosphere. By means of these extensions 43a and 44a sliding connection is made with the ' slots 3| and 32, respectively, in any suitable man ner, as, for example, is shown in the detached View of Figure 6; a pin 56 supported by the lever extension by a suitable device, such as the de vice 55 comprising two spring arms 552L and 55b that clamp the extension therebetween, engages in the slot and thus a sliding and pivotal connec tion is made with the extension of the arcuate lever. Both lever extensions are graduated so that the two devices 55 may be adjustably posi tion. - i (Figure 3) to permit ingress of the atmosphere, the arcuate levers 43, 44 are given a composite motion which is'the resultant of a movement of translation, in counterclockwise direction, as 10 viewed in Figure 2, of the respective ends of the elements 23, 24, and a swinging inwardly toward the center of the mechanism in response to the bending of the elements 23, 24 and due to the rigid connection of the arcuate levers to their 15 respective moisture-responsive elements. , In Figure 2 the elements 23, 24 with their re spective arcuate levers are shown in broken lines in the positions they occupy at the other extreme 1 of response, namely to indicate 100% humidity, 20 and it will be seen that the arcuate levers crossA eachother, the one tending to be wrapped aroundl or against the central axis of the mechanism on one side thereof and the other to the other side of that axis; and to permit the arcuate levers to 25 overlap or thus cross each other without inter ference, they are stepped as at 43b and 44h, re spectively (see Figure 3). , ~ And as the parts undergo a transition in >one direction or the other from the two extreme posi tions shown in Figure 2, in response to corre sponding changes in humidity, or undergo transi tion from either of these extremes to some inter-_ mediate position, the corresponding movement of the respective ends of the elements 23 and 24, as well as degree or extent of their flexing, is am pliñed or multiplied by the coaction therewith of the arcuate levers 43, 44 in coaction again with the sliding connections of the extensions of the latter with the slotted cross-member 30, effecting 40 a rotation of the latter and hence a change in rotary position thereof to correspond to the par ticular flexing of the elements 23, 24 to a given moisture condition of the atmosphere> to which the apparatus is exposed. And the cross-member 30 in turn determines the rotary position of the dial 45 33, with respect to the indicating or arrow heads 31, 38 and the aperture 36 in the front face of the instrument, as seen in Figure 1, the graduations of the dial being, of course, calibrated to suit the characteristics of the elements 23, 24 and to com 50 pensate, if necessary, for any non-uniformity of motion transmission from the ends of the mois- , ture-sensitive elements to the cross-member 30 and dial itself. ` _ ì Referring now to Figure 1, the dial 33 has up 55 standing therefrom a radially extending stop member 48 positioned substantially as shown and itis adapted to coact with two stop' members in the form of studs or pins 49 and 50 (Figures ll, 2 and 3) carried on the inner face ofthe front wall I1 of the cover member I‘B, projecting in wardly from the front wall I1 sufficiently to be positioned in the path of rotary movement of the stop member 48 as carried by the dial 33. ` ' These stop members are so spaced that, when 65 the dial 33 is rotated in clockwise direction, as viewed in Figure 1, to bring the zero indication on the dial in alinement withthe arrow heads 31, 38, stop member 48 on the disk engages the stop member 49 and thus prevents overrunning of the dial, while rotation of the disk in counter clockwise direction to bring the other extreme of the dial, namely the 100% indication, in aline ment with the arrow heads 31, 38, brings the u 2,131,554 4, stop `member 48> on the dial into abutting rela tion to the other stop member 50, thus prevent ing overrunning of the dial in that direction. But this stoppage against overrunning of the dial is effective only upon the dial itself butV im poses no‘strains upon the operating «mechanism or upon the elements 23, 24, for these parts-may overrun the slight amount that may be neces sary because of the friction clutch connection be 10 tween‘the cross-member 30 and the dial 33, as above described. Accordingly, when this stop page comes into action, cross-member 30 may continue to move though this movement will be a slight one ordinarily, while the indicating dial 33 is held against movement. These actions take placeto eiîect a self-adjustment to compensate for Variations or non-uniformity, sometimes un controllable, in the manufacture of the clutch sensitive elements for a quantity of instruments and thereby I am enabled to» overcome such dif ficulties sometimes inherent in the materials em ployed and hence uncontrollable and hence also I am enabled to avoid the need for high precision of construction'and manufacture. Thereby cost v 25 of production is materially lessened. Furthermore, stoppage members 49 and 5S are carried bythe cover member i6 which, it will be recalled, is rotatably adjustable with respect to the casing I0, due to the'bayonet joints I8, i9 30; above described, and the arrow heads 31, 38 are likewise carried by the cover. Accordingly, upon initial assembly or if necessary during the sub sequent action of the instrument, a relative ro tary adjustment between the cover IS and the casing I0 may be made to make certain that any overrunning or underrunning is the same at both extremes of dial or humidity indication. And since, for ordinary use, particularly for household use, it rarely if ever is necessary to - have indications of 0 or 100% humidity of the atmosphere, due to the fact that these condi tions rarely if ever occur in the atmosphere, I am by the above means enabled to achieve sub stantial correctness and accuracy of indication throughout the intermediate ranges within which, particularly in climatic conditions throughout the United States, atmospheric hu midity conditions generally fall. Thus, it will be seen that there has been pro 50" vided in this invention an apparatus in which the various objects hereinbef‘ore noted vtogether with many thoroughly practical advantages are successfully achieved. As many possible embodiments may be made 55 of the above invention and as many changes- might be made in the embodiment labove set forth, it isto be understood that all matter here inbefore set forth, or shown in the accompanying drawing, is to be interpreted as illustrative and so notin a limiting sense. I claim: ' ' ` 1. In an instrument of the character described, in combination, an enclosure comprising a cas ing part and a cover part, means interrelating said parts for relative rotary adjustment, said cover part having a window therein and. having two stop members, a dial bearing visual indica tions rotatably carried by said cover part for presenting an indication to said window accord ing to the rotary position of the dial, said dial having a stop member coacting alternately with said two stop members, the latter being posi tioned in the path of movement of said dial stop member to prevent the dial from overrunning at its two-extremes of movement, a rotatable mem ber, means forming a 'driving connection'between the latter and said dial, said driving connection being capable of yielding or slipping upon halt ing ofthe rotary movement of said dial by said stop members, said rotary member being elon gated and extending diametrically of said dial, means supported in said casing and comprising two radially extending moisture-sensitive ele ments capable of changing their curvatures in response to changes in moisture content of the 10 atmosphere, a pair- of arcuate levers each rig idly attached to the end of one of said elements and to be moved and swung in response to bend ing of the latter, and means forming sliding connections between the respective free ends of' 15 said arcuate levers and said rotary member,. whereby movement of said levers is transformed to rotary movement of said rotary member. 2. In an instrument of the character described, in combination, an enclosure comprising a cas 20 ing part and a cover part, means interrelating said parts for relative rotary adjustment, said cover part having a window therein and having two stop members, a dial bearing visual indica tions rotatably carried by said cover part for presenting an indication to said window .accord ing to the rotary position of the dial, said dial having a stop member coacting alternately with said two stop members, the latter being posi tioned in the path of movement of said dial stop 30 member to prevent the dial from overrunning at is two extremes of movement, a rotatable mem ber, means forming'a driving connection between the latter and said dial, said driving connection being capable of yielding or slipping upon halt ing of the rotary movement of said dial by said stop members, said rotary member being elon gated and extending diametrically of said dial, means supported in said casing and compris ing two radially extending moisture-sensitive ele 40 ments capable of changing their curvatures in' response to changes in moisture content of the atmosphere, and motion-amplifying means forming connections between said elements and radial portions of said rotary member for caus 45 ing rotary movement of the latter in response to curving of said elements. 3. In an instrument of the character described, in combination, an enclosure comprising a cas-ing part and a cover part, means interrelating said parts for relative rotary adjustment, said cover part having a window therein and having' two stop members, a dial bearing visual indica-' tions rotatably carried by said cover part for presentingr an indication to said window accord' ing to the rotary position of the dial, said dial having a. stop member coacting alternately with said twol'stop members, the latter being positioned. in the path of movement of said dial stop member to prevent thev dial from overrunning at its two 60 extremes of movement, a rotatable member, means forming a driving connection between theA Y latter and said dial, _said driving connection being capable of yielding or slipping upon halting of the rotary movement of said dial by said stop` members, saidV rotary ’member being elongated and extending diametrically of said dial, means supported in said casing and comprising two ra dially extending moisture-sensitive elements ca pable of changing their curvatures in response to changes in moisture content of the atmos phere, said rotary member having substantially radially extending slots extending on both sidesk of its axis, and driving connections havingslid ableV engagement with said` slots for causing said 2,131,554 rotary member to respond toflexing of said ele ‘ ments in response to changes in moisture content of the latter. ' 4. In an instrument of the character described, Vin combination, an enclosure comprising a cas ing part and a cover part, means interrelating o î `5 ment of the latter in response to change in shape of the former. ' 7. In an instrument of the character described, in combination, a supporting frame, a rotary l member rotatablycarried by said frame and hav ing portions extending to eachside of its axis, said parts for relative rotary adjustment, said » means supported by, said frame and comprising cover part having a window therein and having two moisture-sensitive elements capable of two stop members, a dial bearing visual indica 10 tions rotatably carried by said cover part for presenting an indication to said window accord ing to the rotary position of the dial, said dial having a stop member coacting alternately with said two stop members, the latter being positioned 15 in the path of movement of said dial stop mem ber to prevent the dial from overrunning at its two extremes of movement, a rotatable member, means forming a driving connection between the latter and said dial, said driving connection being '20 capable of yielding or slipping upon halting of the rotary movement of said dial by said stop members, said rotary member being elongated and extending diametrically of said dial, means supported in said casing and comprising two ra 25 dially extending moisture-sensitive elements ca pable of changing their curvatures in response to changes in moisture content of the atmosphere, said rotary member having substantially radially extending slots on both sides of its axis, arcuate 30 levers each anchored at its one end to a free end of one of said elements, and means coacting with said slots and forming respectively sliding connections between the other ends of said levers 35 and said rotary member. 5. In an instrument of the character described, in combination, an enclosure comprising a cas ing part and a cover part, means interrelating said parts for relative rotary adjustment, said cover part having a window therein and having 40 two stop members, a dial bearing visual indica tions rotatably carried by said cover part for presenting an indication to said window accord ing to the rotary position of the dial, said dial 45 having a stop member coacting alternately with Said two stop members, the latter being positioned in the path of movement of said dial stop mem ber to prevent the dial from overrunning at its two extremes of movement, means constructed to exert a force in response to change in its moisture 50 content, means mounting said means in said cas ing, and mechanism including an overload clutch means for changing the rotary position of said dial in response to changes'in said force. 6. In an instrument of the character described, 55 in combination, an enclosure comprising a cas ing part and a cover part, means interrelating said parts for relative rotary adjustment, >said cover part having a window therein and having two stop members, a dial bearing visual indica 60 tions rotatably carried by said cover part for presenting an indication to said window accord ing to the rotary position of the dial, said dial having a stop member ooacting alternately with said two stop members, the latter being positioned 65 in the path of movement of said dial stop mem ber to prevent the dial from overrunning at its two extremes of movement, a movable member, means forming a yieldable driving connection be tween said movable member and said dial, means 70 constructed to change its physical shape in re sponse to changes in moisture content of the at mosphere, means mounting said last-mentioned means in said casing, and means forming a driv ing connection between said moisture-responsive means and said movable member to effect move changing their curvatures in response to changes in moisture content of the atmosphere, a pair of 10 levers each rigidly attached to the end of one of . said elements so as to be moved and swung in response to bending of the latter, and means forming sliding connections between the respec tive free ends of said levers and said portions of 15 said rotary member for effecting rotation of the latter in response to the action of said moisture sensitive elements. 8. An instrument as claimed in claim 7 in which said frame carries also a scale and datum 20V means, one of which is movable relative to the other, and means forming a connection between the one that is movable and said rotary member. f 9. An instrument as claimed in claim 7 in which said frame carries datum means and scale 25 or dial means rotatable with respect to said datum means, andvmeans forming a driving >con nection between said scale means and said ro tatable member. ' 10. A condition-sensitive unit comprising a 30 mounting post having a plurality of condition sensitive elements mounted thereon and extend ing radially therefrom each of said elements hav ing rigidly mounted on the end thereof. an arcu ate lever arm which has a radially extending 35 portion, a pin-like member adjustably mounted upon each of said radial portions, a pivotal ele ment mounted so as to rotate upon an axis in line with said mounting post and having a .plu rality of slots therein into one of which each ofv 40 said pins may move freely, whereby said pivotal element is controlled in its rotary movement by said condition-sensitive elements. 11. In an instrument of the character de scribed, in combination, a condition-responsive 45 unit, a scale and datum means one of which is mounted upon an adjustable member and the other of which is a movable means and con trolled by said condition-responsive unit, one of said means also being provided with two stops> JO and the other of said means being provided with a single stop, said stops cooperating so as to allow limited movement between said scale and datum means, and a clutch mechanism, said _mov able means being controlled by said condition responsive means through said clutch mechanism, and said stops and clutch mechanism cooperate so as to automatically readjust said movable means under certain predetermined conditions. 12. In an instrument of the character de 604 scribed, an enclosure comprising a casing part and a cover part, said cover part having a win down therein and being adjustable upon said casing part, a condition-responsive unit within said enclosure comprising a plurality of condi tion-sensitive elements mounted upon a control post in said casing, each of said elements ex tending radially from said post and having mounted upon the free end thereof a rigid arm which carries a pin, a scale-carrying element' ro tatably mounted and adjustably carrying a scale, said scale-carrying element being provided with a plurality of slots within each of which one of said pins may move freely, whereby said scale is 6 2,131,554 normally controlled bythecooiperative actionof said plurality of condition-responsive elements. 13._In apparatus of the class described, the combination of, an indicating sheet, a= clutch mechanism, a condition-sensitive element: com prising two strips each of whichv has afiat face, said strips being attached to each other in face to-face relationship,V said element being mounted with. a free end, said freeL end being attached by means of said clutch mechanism to- said indicat ing sheet, andl stop means operatively associ atediwithsaid‘indicating sheet to limit the move- - 5 ment thereof and adjust said indicating sheet. JEAN DE RAYVILLE.