US1622787A - Container - Google Patents

Description

March 29 1927.

G. T.` HoRToN CONTAINER '7 Sheets-Sheet 2 Maio" ina" March 29, 1927.

G. T. HORTON CONTAINER Fle'l Nov. 5.' 1925 7 sheets-Sheet March 29 1927.

l G. T. Hom-ON CONTAINER Fi1ed-Nv-5. 1925 7 sheets-sheet 4 @m9722671 yeafef @7120 Marh 29 1927' G. T. HoR'roN CONTAINER l Filed Nov. 5. 1925 7 Sheets-Sheet 5 1,22 March 29,1927. G L HORTON 6 ,787

CONTAINER Filed ov. 5. 1925 'r sheets-sheet e =llor|zonlalradius al an point d=\/erlccll Olslance from lop of lank al any ponl l? Qaolus of curvalure al any poinl in plane perpendicular lo paper l =Qaclius ofcurvalurealany poinl in plane of paper D =Dressure al any panf DAveraae pressure on horizonlal seclion alany poinl- VOlurneArepresenls lolal upward pressure due ro aas Volume 5 Pepresenls lolal u ward pressure a'ue lo l uid Volume C represenls folal downward pressure due ro l uid Tl: lress in shell al any ponlln horizonlal direclon T2 =5lressln snel lal any polnl lnverlcal direclion I ilu/f3 #eww March Z9 1927.

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m R 1 000: 000 00 0000 000m 000m 0E 000005000000 00.0 00.0 0 0.@ 0&0 090.000 000 R m 5.. 000 000 009 0000 0000 0000 NQ 00000080000 00.0 00.0 .0 .0.00.00 :2000000 0n m m 000 000 00:4` 00.00 0000 0000 00. 0000000000000 00.: 02. Q @n 000 0N 090.000

T. w d 03u 09 0000 0000 0000 000m @n 000i@ 0092 00.: 00.. 0 0002.0 S0 00u 000 m 00 0m 0000 00.00 002` 0000 E. 0000.0 0000 00.9 00.0 0 0.0w0.000. 0 0 0 N G m 0 O 000m 0000 0000l 000m 0 0 o 00.0 0 0 0.00, 0.000 0 0,

00M@ @www @l 00.00.00 000000 00.00. 0.30m 0 0.50m x0 Patented Mair.l 29, 1927.

UNITED STATES PATENT oFFicr..

GEORGE T. HOBTON, F CHICAGO, ILLINOIS.

CONTAINER.

Application ledvNovember 5, 1925. Serial No. 67,094.

,This invention relates to' improvements in containers and is'here shown as embodied in a containerfespecially adapted for holding liquids under pressure. For example, in the storage of Volatile liquids "such as gasoline.

'16 in the tank a certain amount of internal pressure depending upon the vapor pressure of the vapor in the event that the maximum 15 and the temperature.

of the liquid stored. The-amount of vapor pressure, vof course, depends upon several factors` such as the volatility of the liquid If the tank or con'- tainer, however, is closed and able to withstand the internal pressure created, loss by `evaporation is prevented.

One of theobjects of vapor pressure. Where the container is vvdesigned to withstand a certain maximum .vapor pressure, la safety valve, or other suitable vent, may be .provided to permit escape pressure should, for some reason or other, be exceeded. i

Obviously, in addition to this vapor pres surewhich is the same at all points Jon the shell. there is the additional pressure caused by the weight of the liquid itself or the head. .This pressure, obviously depends upon the density or weight'of the liquid, and `varies at different points on the container depending upon the head of the liquid or height of the liquid above kthe particular point.

` One of the principal objects of my invention is to provide a cl'osedcontainer of the 40 kind described, for the storage of liquids under pressure, of such a shape that the-vertical tension is .substantiallyt'he same at4 -every point on the shell. In a container o f this type. the horizontal tension is always less than the vertical tension. By tension,

that this tension will be substantially the' I mean the stress on the shell tending .to make it part, break', or rip at a particular point. 'Ihere is a great advantage in making a container of this kind of such a shape same at every point; because whenso made, the material of which it is composed may be of a. uniform thickness.- For example, by the use of my vinvention a closed tank may be made designed for the storage, for example, of gasoline of a certainspeciic gravmy invention is to 20 design a container which will withstand such ity with a certain vapor pressure. :Thel

shape of the tank, if made by the use of l my invention, would be such ,that when filled with gasoline of the given density, and subject tol an internal pressure equal to the given vapor pressure plus th-e liquid pres! sure of the gasoline, the tension or stress in a vertical direction on all points of the shell would be the-same. In'such a tank, therefore, material of a uniform thickness could be used. Since,- in a container of this type, the horizontal tension is always less than the vertical tension, it is sufficient if such vertical tension is substantially th saine at every point on .the shell. tension is always greater than the horizontal tension because, at every point on the shell, the radius of curvature in the vertical plane is less than the radius of curvature in the plane at right angles thereto. The shell then must be strong enough to withstand such vertical tension, and thehorizontal tension can be disregarded. `If such vertical tension, which is always greater, is substantially the-same at all points on the shell, the shell may be made of material of a uniform thickness. Since, in making containers of this kind, it isnecessary to-have the material thick enough to withstand only the vertical or the horizontal tension, whichever is greater; and since the lesserof these two tensions always may be disregarded.; hereinafter, in using the term tension only, it is to be understood that I refer always to the greater of the two tensions. It is also to be understood, that in containers embodying the features of this invention, that the greater of such two-tensions is always the vertical. VIn speaking of the vertical plane atv any point on the shell, I refer to such a vertical plane passing through a line normal to the surface .'at suclrpoint; andin speaking of a plane at right angles to such vertical plane, I also refer to a plane passing through a line normal to the surface.

One of the features of the invent-ion,` is- The Vertical is no vapor pressure, or other internal pres- Since this space is comparatively small and sure, except that resulting from the weight at the top, that any pressure which might orliead of the liquid itself, the tension on result from the Weight or head of liquid the shell is always greater near the bottom therein is negligible. In any event, as Willi than at the top. This is due to the increase be seen hereinafter, in the practice of my inm the weight or head of the liquid toward vention, in determining the shape Of the the bottom. In such containers, therefore, container, -it is assumed that the container the shell must be made thicker at the botis entirely filled with liquid; with the result tom than at the top. In the case of a conthat, if, in tact, there is a space at the top tainer such as contemplated b-y this invenfree from liquid, it merely follows that the tion, however, where there kis a certain pressure or tension of the shell at the top amount of vapor or other internal presand surrounding the space is assumed to sure inside of the shell in addition to the be slightly larger than it actually is. Since i 'pressure caused by the Weight or head of the the metal is thick enough to withstand the regarding the same, it merely liquid itself, I have vfound that by making tension so computed, it is obvious it is also the container in the proper shape, the tenthick enough to withstand any lesser tension can be made to be substantially the sions that there might be at the top if the same at all points on .the shell; with the retank isnot entirely filled with liquid. sult that material of `uniform thickness can It is obvious that, although a tank be debe used throughout. Y signed for a 'certain liquid and a certain It is to be understood, also, that although vapor pressure, that in actual use there may I speak of vapor pressure, I do not intend bc variations in the density of the liquid to be limited to this particular kind of intercontained in the tank, the amount of liquid nal pressure. Broadly, my invention conin the tank, or in the actual internal prestemplates the construction of a lclosed consure. In the practice of my invention, theretainer adapted to hold a liquid, there being fore, the container preferablyfshould be d econfined in said container a certain internal signed for a certain liquid and a certain pressure in addition to the pressure caused t normal vapor pressure; but should have suf- `by the mere Weight or head of the liquid. ficient rigidity and suficient excess of ten- This internal pressure may be caused by sile strength to permit suitable variations vapor pressure from the liquid itself, or may from the normal conditions for which the arise from any other cause. For example, it tank is designed. Suitable safety. valves might be desired to make a container adapti or vents may also be provided to relieve ed -to hold Water, there being in said contain-4v pressures vWhich might exceed the marer also a certain amount of air pressure. In gin ot safety.

such case, the Weight of the Water being In general, theshape ot the tank resembles known, and the air pressure also being the shape of a drop of lmercury resting on known, by the practice of my invention, the a dat surface such as, :tor example, glass.

vcontainer could be so shaped that the tension Or it may be stated that in general the conat all points Would be substantially the same ytainer will have somewhat the same shape thus permitting the use of material of a unithat would naturally be assumed by a conform thickness throughout. Such a containtainer with a ilexible, wall if filled with a er for Water with additional air pressure given liquid and also containing the given therein might be used, for example, in convapor or other internal pressure. That is, nection with water supply systems in which it is spheroidal in shape with a flattened the storage tank is locatedat a lower level bottom, or, it may be described as being a than the outlets; and a certain amount of flattened'sphere with a flat circular bottom. air pressure introduced into the tank lin It is also a solid of revolution about a verorder to cause the water to How up to the tical axis. The relative proportions of'the outlets at a desired pressure. tank will vary depending upon the weight In speaking of a container for a liquid of' liquid it is to contain and the amount having inside an additional internal pressure of vapor or other internal pressure inside such as vapor pressure, itis to be understood, 'of the tank. It may be stated, in general, also, that there may be, and usually must be, that increasing the vapor pressure tends to a certain amount ofspace at the top of the make the container somewhat liiglier'in procontainer free from liquid. Theoretically, portion to its width; and increasing the this space may he 'exceedingly small and pos' weight of the liquid inside tends to make sibly `eliminated.` In determining the shape it somewhat wider in proportion to its ofl the container, I am disregarding this height. VIn other words, the particular space at the top which is 'free from liquid. shape will dependv upon the particular This space may be quite small; and diS- liquid and particular vaporpressure conollows that ysidered vas normal for which the tank is I disregard the absence of pressure resulting designed. I will show how the particular from the absence of weight or head of liquid u n llthis space.' Itis obvious/however, that any liquid and any vapor or otherintershape for any tank canbe determined forv lll() nal1 pressure which may be chosenas norma Aftervthe shape has been determined, the tank may be built in a number of ways; preferably, by riveting, welding, or otherwise fastening. together plates, each of .which has been previously formed to the required curvature for its position in the `completed structure.

In the accompanying drawings, Figuie 1 is a diagrammatic central vertical sectional view showing the shape of a container designed for a liquid weighing 36 pounds per cubic foot and a vapor pressure of 10 pounds per. square inch, Fig. 2 is a similar View showing the shape ota container designed for a fluid weighing 36 pounds per cubic foot and a vapor pressure of 50 pounds per square inch, Fig. 3 isa similar view of a container for fluid-weighing 144V pounds per cubic foot and a vapor pressure of 10 pounds per square inch, Fig. et is a diagrammatical vertical section ofva completed tank made in the shape shown in Fig. 1, Fig. 5 is a view in perspective of a container similar to the one shown in Fig. 4, Fig. 6- is a diagram showing a graphical method of determining the shape of a container ern-K' 4bodyingl the features of my invention, and

Fig. 7' is a table showing the properties of' y the curve shown in Fig. l6 and the theoretical stresses on a container shaped accordlng to such curve.

I will now describe more shape of a tank embodying my invention. The density or specific gravity of the liquid to \be stored is known. The vapor pressure y `point of the tank. On the line A-Z there or other internal pressure (in addition to f that caused by the weight of the liquid) f which the tank is to withstand as normal is also` known. Assume that thisvapor pressure is ten pounds per square inch and that a cubic foot of the liquid weighs 36 pounds.` r In designing the tank it may be assumed that it is fllor substantially `full of liquid as a normal condition. These are the conditions assumed in [plotting the curve shown y in Fig. 1. The line A-Z indicates the vertical central axis of the tank extended downwardly. A therefore indicates the topmost is laid off the line A-Y which is the radius of curvature at. A; This radius may be taken any desired length and Adetermines the capacity of the tank. 'As thev capacity is made larger, however, the tension on the strength to withstand the resultingtension.-

shell increases and consequently stronger material must be used. The radlus A-Y 1s chosen, therefore, to give the desired c a-v pacity provided the material has suliicient Since the completed tank is in the shape of r. a' spheroid, there are obviously at each point two curvatures in planes at right angles to in detail the' r method of determining the curvature vor length of a line normal to. the curved surface at any point on'the surface from such point produced until it meets the line A-Z. In otherv words; for any points `on the surface 1', will be equal tov*J produced until `it intersects vthe line A-ZL At the point A obviously r2 and r, will be equal. Under the assumed conditions the pressure at A will be ten pounds per square inch since this was taken tol be the normalv internal pressure. There being no height ofliquid above A, or head, the only pressure at A will be ten pounds. r2 at A is taken as'the distance A-Y which, as stated before, may be any desired distance depending upon the capacity desired. Since 'r1' is 'equal to r2 at A, fr, at A is also represented by the distance AfY. i y

The vertical tensionat `any pointsonv the shell equals the pressure at thatpoint divided by4 y T2 (mi2 that is, 0 T P L+ 2 T2' (T02 jwhere P represents pressure' and Tthe vertical tension which, as has been stated above, Y

is the greater tension. Since the'pressure at Ay is 10 pounds per square inch,

-T-l-Lici As stated, r2 at A is the chosen length and in Fig. 1 this length is taken as 50 feet, or 600 inches. l At A, r2 andl r1 are equal in length, consequently, the tension' at A-inay be expressed by theequation 1 +r 600 o (60m2 Solving this equation gives T2300@ The if T= tension being kndwm the proper thickness andrsiz'e of material can bel chosen to withstand such tension. With the'radius r2 at 600 and the center at Y, a short arc A--B is drawn. It will be Seen that the point B is I somewhat lower than the point A. The distance A-Y represents 600 inches. The height of the point B can be determinedl by measurement. Assume that, point B is found to be .50 foot lower than point A'. Then the pressure at B will be 10.125 pounds per square inch. This figure is found in the following manner. Under the assumed conditions the internal pressure orvapor pressure is ten poundsper square inch and this is the same at all points on the shell. Under the assumed conditions` also, the weight of the liquid in the shell is .25 pound per square inch for. each foot ofhead or height of the liquid. The head at B is .50 foot. Consequently, the

pressure from the'. head alone at B is .125`

pound per square inch. The total pressure at B is ten pounds plus .125 pound or 10.125 pounds per square inch. The vertical tension at any point in the container may be l expressed by the equation inches.

. P T: W

E+ (WO2 i The are A-B was drawn with r2 taken at- \600 inches. This Was the correct radius for the arc A. with the tension at A equal to 3000. Since the container is to be in such a shape that the vertical tension or T shall be substantially constant at 3000, it will be seen that r2 at B does not-equal exactly 600 4but is slightly shorter. The exact length of-r, at B can, however, be calculated from the formula i l l T2 y New in which Pb `equals the pressure at Bj I wish to keep T substantially constant at 3000. P at B equals 10.125. r, at B is the r length of r2 extended until it .intersects the line A-Y. This distance is substantially 600 inches. Substitutingthese known Values in the equation just given, and we get the equation 1 2 ett-600V meagre? Pc Tri;

where PC equals the pressure at C. The pressure at U will be 10 pounds per square inch', (the internal pressure which is the same all over) plus the pressure due to the head at C. By measurement, it will be found that at C there is approximately 3 feet of head. This will give a pressure of .75 pound per square inch due to the head so that the total pressure at() willbe 10.75. T is to be ke t constant at 3000. r1 may be measured an tially 562 inches. Using the same equation as before and solving for .r2 gives r2 at C equal to 499 inches. With this as a radius, the arcv C-D is then drawn taking the center on the line C-Yb. This center may (be referred to as YC. The true value of rg at D is then calculated in the same manner and the are D E drawn. In a similar manner the curve is completed. For example, 1-,

' points P. Q, and R, it becomes horizontal n. and thus indicates the bottom of the tank.

If desired, the curve can be-constructed from amathematical equation instead of graphically as shown. lf this is done, the equation or formula of the curve will have tobe derived from the equation is derived inthe following manner: In such equation T2 1s the vertical tension which is the greater. In such a container will be found to be substany where T1 is the horizontal tension, fr, the radius in a plane at right angles to the pape1 and r2 theradius in the plane of the paper. ln a container of this kind We note that at any one point Where T1 equals the horizontahtension. and- T2 the vertical tension, and 7', the radius of curvature in a plane at right angles to the paper and r2 the radius of curvature in the plane of the paper.

The approximate shapeof the curve can also be found 'by using the equation P T= `y ri r2 in which T is theltension,.at any point assuming the vertical and horizont-al tensions to be the'same. This is the equation for expressing the surface tension in a drop of liquid, such as, for example, in a drop of mercury and from it, the shape ofthe drop can be computed. This equation .is theoretical, however, and is notexact for de termining the shape Of-a steel or other container.

In Fig. 2, I have shown the shape of a ktank found in the same manner, assuming-that the liquid' Weighs 36 pounds per cubic foot and that there 'is a normal vapor pressure of 5() pounds per squareinch.

In Fig. 3 I have shown a form `or shape for a container` constructed inthe same manner but designed to hold` normall a liquid Weighing 144C pounds per cubic foot and to contain an internal vapor or gas pressure of ten pounds per square inch.

.From an examination of the curves in Figs. 1, 2 and 3, itWill be seen that as the internal-pressure in relation to the density of the liquid is increased, the tanklbecomes more spherical. As the Weight or density of the ,liquid is increased relatively to the internal pressure, the tank attens out.

In Fig. 4 there is shown a diagrammatical vertical cross-section View of an actual tank of the shape shown by the curve in Fig.

1. It will be seen that the curvature of the tank conforms to the curvature shownin the graph in Fig. 1. The tank here,- shown is built to normally hold a liquid Weighing 36 pounds per square foot withv an internal pressure of 10 pounds.

The radius of curvature .at A is taken at feet or 600 inches. The tension at A is therefore, 3,000 pounds.

Since the curve isconstructed as described above, the vertical tension is ylikewise 3,000

pounds at any point in the shell, assuming the tank to be `substantially full of the liquid K With an internal pressure yof 10 pounds.

Since the vertical tension is the same at all points, metal of uniform thickness may be used. It should, of course, be strong enough to withstand the giventension. If the tension is too great, the radius of curvature/aty A may be made less with the result that the tank Will be smaller in capacity and the tensionless. The radius at A may be chosen as desired togive the-requisite capacity provided metal of requisite strength is used. The tank as actually constructed may also contain a central vertical pillar or strut at A as indicated by the reference numeral 50 and also other vertical struts 51 at or near the periphery of the fiat circular base ofthe tank. he strut 50 alone maybe used, or the struts 51 aloneor both together inorder to give' any desired eXtra rigidity or strength to support the tank When empty or partially empty or When the normal internal pressure is exceeded or the tank contains a liquid having a Weight or density greater than that for which the tank is normally designed.

The upper ends ofthe struts 5() and 51 may be attached directly to the shell -or such upper ends may be joined by curved meinbers 52, 52, upon which the upper plates of the shell mayrest. The members 52, if desired, may be joined t0 the shell by brackets 53, 53 as shown. i

It is to be noted that a tank shaped in laccordance with my invention has a dat bottom as indicated by 61 so that it may rest on a flat surface and be entirely selfsupporting thereon. When thus resting, and filled with liquid at the normal' internal lll) pressure, the greater, or vertical tension at all points Will be the 'same and there will therefore be no undue stresses or strains at any point. The tank may be\buil`t,.there fore, Without the use of any outside `posts or members to support the same.

method 'for determining the shape of a con- In Figf I have shownanothe'r graphical "duced from the point 1.

horizontal section at that point.

tainer in the practice of my invention. I am here showing, as in Fig. 1, the shape for a container adapted to normally contain liquid weighing 36 pounds per cubic foot and an internal vapor pressure of ten pounds per square inch. As in Fig 1, `I lay out a center line A Y and produce the same upwardly. On this line with point Y as a center a radius Y-A is taken, A lying at point 1 at the center of the top of the container. With this radius the arc 1 2 vis described. X equals ythe horizontal radius at any point. For example, X is ahorizontal radius from 1 to a verticalline produced upwardly from point 2. cl equals the vertical distancejfrom the top of the tank at any point. For example, al is the vertical distance from point 3 toa horizontal line pror, equals the radius et curvature at any point in a plane perpendicular to the paper. r2 equals the radius of the curvature at any point in the nlane of the paper. I equals the pressure at any point. PA equals the average upward pres sure on the horizontal section at any point. T2 equals the vertical tension or stress at any point. T1 equals the horizontal tension or stress at any point.

Y In 'Fig 6 the volumes are indicated by the shaded areas as follows: Volume A when eX- tended as far to the left as afvertical line from a ,given point represents the volume ot the given liquid whose weight equals in amount the total upward gas pressure on a Volume B when extended as far to the left as a vertical line from a given point represents the total i upward pressure from the weight or head.

of the liquid'at that point. Volume C when extended as far to the right as a vertical line above a given point represents the downward force or pressure from weight or head of the liquid on a horizontal section at that point. That is, for example, volume A for the point 3 is represented only by that portion of the rectangle indicated Volume A .lying to the right vof the line 3 3. Likewise, for example, volume B for the point 5 is represented only'b'y that portion of the area marked Volume B lying to the right of the. line 5 5. Likewise, for example, volume C for the point 10 is represented only by that portion` of the area marked Volume C lying -to the left of -the line produced upwardly vertically from the point 10., All actual volumes are computed by rey volving the represented area about the vertical central axis. A

For points -on theupper portion of the curve the total upward force equals volume A plus volume B. For pointson the` lower portion of the curve then total forceain a vertical direction is volume A plus volume B minus volume C. When volume A plus iv'olume B equals volume C there is no vertical force and the curve becomes tangent to the bottom.

In making the curve, as stated before, an arbitrary radius, for example, 50 feet is taken for the distance A Y and a short are 1 2 described. At this point 2,`then, volume A and volume B can be determined graphically as abovev described. There can, therefore, be calculated for point 2 volume A and volume B. Volume A represents the internal vapor or .gas pressure. This is here shown as equivalent to an additional head or height of liquid of the same density as con tained in the container. Under the assumed conditions the gas pressure is ten pounds per square inc'h and the liquid weighs 36 pounds per cubic foot. Consequently, a gas pressure of ten pounds per square inch would be equivalent to an additional head or height zontal section at this point can be determined. In drawing the arc 1 2, the arbitrary radius of 50 feet was used for r2. At this point, from the average pressure at point 2 caused by volumes A and B at this point, the exact length of r1 can be com- `puted so that the vertical tension at 2 will not exceed that at 1. With this length as a radius and point 2 as a center strike an arc so that it intersects the line A. Y. The line between this intersection and point 2 will be the' new r1. By new r1 I mean the r1 vfor the portion of curve 2 3. The intersection of the 1, for the curve 2 3 with the r1 for the curve 1 2 will obviously determine the center of curvature and therefore the (r2) for the portion of the curve 2 3. The shape 'can then be extended to the point 3 by drawing the arc 2 3. vThe process is merely repeated for the yremainder of the curve. The determination of the correct 1', at each point can be found by the use of the engineering formula T2 A D in which T2 is the vertical stress at the point, PA 'is the averagev unit pressure on a horizontal section in an upward direction, and 'r1 is the radius of curvature at right angles to the plane of the paper.

After point 8 is reached, the pressure at any point, for example, at point 9, is found by taking the sum of volumes A and B for such point and volume C at such point.

In Fig. 7 I have shown a table indicating the properties Aat the curve shown in Fig. 6, and the theoretical stresses at the different oints-thereon in accordance with the method i Just described.

While I have shown and described cert-ain subtracting therefrom I embodiments of my invention, it is' tobe understood that it is capable of many modifiations. Changes, therefore in the construction and arrangement may be made without departing from the spirit and scope` of the invention as disclosed in the appended claims, in which it is my intention to claim all novelty inherent in my invention as lbroadly as possiblein 'view'` of the prior art.

' Vhat I claim as new, and desire to secure by Letters' Patent, is:

l. A closed container substantially in the shape of a solid of revolution about a vertical axis and having a supported bottom,

said container so shaped that when substan-4 tially filled With a normal liquid and containing a normal internal or vapor pressure. the radius Vof curva-ture at each point on the `shell above the supported bottom in a vertical plane, through a line normal to the shell at that point, equals the vertical tension at such point .times the square of the radius of curvature in a plane at right angles to the first mentioned plane and also passing through said normal line, divided by the pressure at such point times the square of said second mentioned radius minus said vertical' tension times said 'first mentioned radius. Y2. A closed container substantially in the f shape of a solid of revolution about a vertical axis, so shaped that at each point on the curved portion ofthe shell the radius of curvature in a, vertical plane, through a 3:, line normal to the shell at'that point, is less than the radius of curvature in a plane at right angles to thefirst mentioned plane and also passing through said normal line.

3. A closed container substantially in the shape of a solid of revolution ,about a ver- 'tical axis, so shaped that ateach point on the curved portion of the shell, the radius ot curvature in a vertical plane, through a line normal to the shell at that point, is less than the radius of curvature in a plane at right angles to the first mentioned plane and also passing through said normal line; and in which the radii of curvature at suc- `cessive points from the-top of the shell to- Ward the bottom on the curved portion ot' said shell in a vertical plane, through lines normal to the shell at such points, are successively shorter.

4. A closed container substantially in the shape of a solid of revolution about a vertical axis and having a supported bottom, said container so shaped that at each point onf the shell above the supported bottom the radius of curvature in a vertical plane, through a line'normal to the shell at that point, is less than the radius of curvature in a lane at right angles to the first inentione plane and also passing through said normal line.

61; 5. Aclosed container substantially in the shape ofia solid of revolution aboutla ver- A tical axis and. having a supported bottom,

said container being sov shaped that at each shell'at that pofi'nt, is less than the radius( of curvature in a plane at right angles to the first'mentioned vplane and also passing through said normal line; said container also being so shaped that the radii of curvature at successive points on the shell from the `top thereof down to the supported bottom in a vertical plane, through lines' normal to the shell at such cessively shorter. v

y 6. A closed container substantially'in the shape of a solid of revolution about a verti;v cal axis'vand having a supported bottom, said container so'shaped that/at` each point on the shell-above the supported bottom the radius of curvature in a vertical plane, through a line normal to the shell at that point, is less than the radius of 'curvature in a plane at right angles to the first mentioned planeand also passing throughsaid normal line; said container also being so shaped that the radii of curvature at successive points on the shell from.,the top thereof down to the supported bottom in a vertical po1nts, are sucsuch points, are successively shorter; and said container also being so shaped that the radii oflcurvature at successive points on the shell from the top thereof down to the supported bottom, in planes at right angles to f said vertical plane, and also passing through lines .normalto the shell at such points, are

successively shorter from. the top of said shell down to the point of its greatest horizontal diameter, and successively longer from said point down to the supported bottom.

7. A closed container substantially in the shape of a solid ofrevolution about a verti-J cal axis and having a supported bottom, ,said container being so shaped thatl the radii of curvature at successive points on the shell from the top thereof down to the supported bottom in a vertical plane, through lines normal to the shell at such oints, arer successively shorter; said container also being" so shaped that the radii of curvature at successive points on the shell from the top thereof down to the su-pported bottom 'in planes at right angles to said vertical plane, arid also passing through lines normal to the shell ,at such points, are successively shorter from the top of said shell down to the point of its greatest horizontal diameter and from such point' are successively vlonger down to the supported bottom.

8. A closed container substantiallyin the shapeof a solid of revolution about a vertical axis and having a supported bottom, said container being so shaped that the radii of 95 plane, through lines normal to the shell at curvature at successive points on the shell from the' top thereof down to the supported bottom in planes at right angles to a vertical plane, and passing through lines normal to the shell at such points, are successively shorter from the top. of the shell down to the point of its greatest horizontal diameter and from such point are successively longer down to the supported bottom.

9. A closed container for a volatile liquid substantiallyin the shape of a solid of revolution about a vertical central axis, every vertical central cross-section of which is an area bounded by a curve the bottom portion of which is flattened and of which the arcs from the flattened portion to the top Centralv point have successively longer radii, the

Whole curve being a function of the Weight and pressure of a liquid for which the container is designed. substantially as set forth.

10. A closed container for a volatile liquid substantially in the shape of a solid of revolution about a vertical central axis, every vertical central cross-section of Whichis an reame? area bounded by a curve the bottom portion ff of which is flattened and of which the arcs from the flattened portion to the top central point have different radii, the Whole curve being a function of the Weight and pressure i of a liquid for which the container is designed substantially as set forth.

l1. A closed container for a volatile liquid substantially in the shape of a solid of revolution about a vertical central axis, every vertical central cross-section of, which is an area bounded by a curve the bott/om portion of which is flattened and of which the arcs .from the flattened portion to the top central point have different radii, those of the upper `arcs being substantially longer than those

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