referring now to the drawings , wherein identical reference numerals are used throughout the various views to indicate identical elements , the tank of the present invention according to fig1 comprises a plurality of intersecting cylindrical shell portions 1 which cooperate with portions of spheres ( closing caps ) 2 and portions of cylinders 8 to produce a supply tank having a generally cubical shape . as shown in fig1 each corner of the tank consists of three intersecting cylinders which are disposed at an angle of 90 ° with respect to each other and provided with a spherical closing cap 2 . the tank has eight right - angled corners and thus comprises 12 intersecting cylindrical portions , eight spherically shaped closing caps and six cylindrically shaped closing caps . the cylindrical shell portions formed from cylindrical shells are of equal diameter and length with four of the shell portions forming a side of the tank . the shell portions are formed by removing an arc length section of the circumference of each of the shells and also by removing that portion of the ends of each of the shell portions defined by diagonally intersecting planes produced at both ends of the shell portions resulting from the intersection of three shell portions placed perpendicular to each other at each corner to form the generally cubically shaped vessel . each aperture formed by three shell portions intersecting at each corner is closed by a spherically shaped cap . each cap is that portion of the surface of a sphere of equal diameter to that of the cylindrical shell portions so that a continuous tank surface is found when the caps are placed in the apertures . the four cylindrical shell portions making up each side of the cubical tank also define an aperture in the middle of each of the sides . these apertures are closed by the cylindrical closing caps . these caps are formed by four identical parts of a cylindrical surface connected together to form a cylindrically shaped cap . the base of each of the cylindrical caps forms a continuous surface tangent with each of the apertures defined by the shell portions and extend inwardly into the tank . fig2 diagramatically shows how a cylinder 3 which is subjected to a uniform internal pressure will be stressed in the circumferential direction . fig3 diagramatically shows how the cylinder 3 would deform 4 if a portion of the cylinder 5 was removed but the remaining portions thereof were still subjected to a uniform internal pressure . in order to maintain the remaining portion of the cylinder 3 in an equilibrium condition , forces 6 and 7 would have to be applied to the edges either tangentially , or normal to the cylinder , respectively . a continuation of the forces in both directions would also be acceptable . fig4 shows how the independent cylinders 1 are connected by closing caps 8 which are constructed from four substantially equivalent portions of a cylinder 9 which cooperates in a manner shown in fig4 a . the type of deformation due to internal pressure a tank cross - section would be subjected to in the area of the closing caps , is indicated in fig4 by numeral 10 . fig5 is an external elevational view of the tank of the present invention showing four cylindrical portions 1 , four spherical caps 2 , one internal cylindrical closing cap 8 , support pedestal webs 11 and support plate 12 which transmit the total load due to the weight of the tank and its contents to the supporting structure . openings are provided in the top of the tank , when required , for pump installation 12 and for access aperture 13 which provides access to the tank . fig6 is an external plan view of the tank of the present invention showing the four intersecting cylinders 1 , four spherical closing caps 2 , one internal cylindrical closing cap 8 , two pump installations 12 and one tank access aperture 13 . fig7 is a sectional view taken along lines 7 -- 7 of fig5 and shows , in section , four horizontal cylindrical portions 14 , two horizontal cylindrical portions 15 in elevation , two vertical cylindrical portions 16 , two spherical closing caps 2 and one internal closing cap 8 . it can be seen from the above described drawings and the above description that the boundary of the tank of the present invention comprises three distinct shapes formed from rotationally symmetrically plates which are joined together in a continuous manner , with the exception of where the support pedestals 11 , the pump openings 12 and the access opening 13 pass through the shell , enabling the stress that the structure is subjected to , that is , the support loads , the internal pressure and the thermal loadings , to be accurately determined . this advantageous feature satisfies the requirements of various governmental regulatory bodies for acceptance of the tank of the present invention as a single walled pressure vessel for marine application without the need for a liquid - tight secondary barrier . the unique shape of the tank of the present invention gives it considerable inherent combined strength . it is not necessary to support any portion of the tank by external or internal structure other than that already described hereinabove . however , the weight of the tank and its contents must be transferred to the supporting medium . this can be accomplished by simply allowing the bottom of the tank to bear directly on the support medium . in a preferred embodiment of the present invention , where the tank will be insulated by a non - load bearing type of insulation on the external surface of the tank , support pedestals 11 are utilized at each corner of the tank . fig8 shows a plan sectional view of a support pedestal taken along lines 8 -- 8 of fig5 . the upper free edges of the corner web plate 17 , the internal web plate 18 and the pedestal cylinder 19 are stiffened by a horizontal web and face plate 20 . the pedestal web plates and cylinder are connected to the load distribution plate 12 &# 39 ; which transmits the load of the tank and its contents to the supporting structure . a closing plate 21 , shown in fig9 is fitted inside the hollow pedestal cylinder 19 at the level of the tank bottom . if considered beneficial , the closing plate 21 can be located below the level of the tank bottom thus providing a drain well for pumps , thus enabling the complete stripping of the tank . thus , the hollow pedestal cylinder 19 is adapted to receive a deep well or submersible pump for removing the contents of the tank . drain holes 22 are provided in the hollow pedestal cylinders at the lowest part of the tank for continuously draining the contents from the tank into said hollow pedestal cylinders . as stated above , the closing plate 21 may be slightly lower than the bottom of the tank to form a drain well for completely removing the contents from the tank . an aperture 23 is provided in the support plate 12 &# 39 ; to provide access to the space below the closing plate 21 and to facilitate fabrication and the insulation of the space defined by the closing plate 21 and the support plate 12 &# 39 ;. the pump installation 12 extends from the top of the tank into the hollow pedestal cylinders 19 . fig9 a is a perspective view of the support pedestals shown in fig8 and 9 . fig1 is a cross - section through a ship designed to use the tank of the present invention for transporting liquid natural gas . fig1 shows a hull structure made up of a double bottom which defines bottom wing tanks 24 with sloping inner bulk heads to provide a drain well to collect any liquid in the event of leakage , side wing tanks 25 and a weather shield 26 . the actual containment tank 27 advantageously would be insulated on the outside and insulation 28 covered with a sheething such as fiberglass or plywood sheets can be installed on the inner surface of the vessel and the weather shield to protect the structure from the direct effect of leakage . the weight of the tank and its contents are supported by the pedestal plates 12 &# 39 ; which are in turn supported by hardwood 29 fitted on top of the tank top 30 . the lateral support and vertical restrainment of the tank is provided by sloped bearing surface arrangements 31 disposed on the tank and on the ship &# 39 ; s structure as can be better seen in fig1 to 14 of the present application . the tanks fits into a horizontal stringer 32 , which is at the same height as the pedestal horizontal corner webs 33 but with sufficient clearance for the installation of the tank . fig1 is a plan view taken along lines 11 -- 11 of fig1 , showing in detail , how the supporting pedestals cooperate with each other and with the tank structure . fig1 shows the details of the lateral and vertical support retainers including part of the horizontal stringer , part of the tank wall 1 and part of the pedestal horizontal corner web 33 . at each support location 31 are provided two bearing pads , that is , a support element 34 attached to the tank and a cooperating supporting element 35 attached to the vessel . these supporting pads have a common slope based on the relationship between the contraction of the tank and the surrounding structure during cooling and containment of the refrigerated liquid natural gas . this insures that adequate lateral support will be provided for the tank in all of its possible states . an insulator such as hardwood 36 , as best seen in fig1 , is provided between the two bearing or support pads 34 and 35 . as stated above , the tank fits into the horizontal stringer 32 with sufficient clearance 37 for the installation of the tank . fig1 and 14 show how the slopes of the pads in both the vertical direction 38 and the horizontal direction 39 are determined . these figures indicate , diagramatically , how the tank contracts due to the storage of low temperature liquids in said tank . if the surrounding ship &# 39 ; s structure is of the same material as that of the tank and is subjected to the same uniform temperature differential , then there would be no relative movement of support points on the tank and ship &# 39 ; s structure and accordingly , the tank could be mechanically secured to the ship &# 39 ; s structure . however , because the tank is insulated to reduce heat inflow to a practical minimum and , because , in some instances , the ship &# 39 ; s structure is also insulated to prevent it from being subjected to low temperatures , the movement of the support points on the tank and on the ship &# 39 ; s structure is not the same . the present invention accommodates this relative movement between the tank and the ship &# 39 ; s structure in both the vertical and the horizontal directions by aligning the slopes of the bearing surfaces in the vertical and horizontal directions in the direction of contraction . thus , to account for the relative movement between the tank and the ship &# 39 ; s structure due to different temperature differentials and construction materials , the length of the bearing surface of the support pads 35 on the ship &# 39 ; s structure is made longer then that of support pad 34 which is connected to the tank , in accordance with the ratio of the relative movement of the tank with respect to the ship . the slopes of the vertical bearing surfaces 38 and the horizontal bearing surfaces 39 are determined as shown in fig1 and 14 . the tank , in contracting from its size 40 at ambient temperature to its size 41 at a much lower temperature , the tank support pad 34 moves in toward the center of the tank and down toward the bottom pedestals . knowing the temperature differential and the properties of the tank material , the slopes can be determined either by calculation and / or graphically . it should be noted that in the vertical direction , the bottom of the load distribution plate 12 is the fixed reference point for the contraction whereas in the horizontal direction the fixed reference point is the vertical center line of the tank 42 because said reference point does not move . fig1 and 16 are exploded isometric views of the support pads , fig1 also showing the hardwood insulator 36 on both bearing surfaces of support pad 34 . fig1 shows a sectional elevational view of the cooperation of the support pads 34 and 35 taken along lines 17 -- 17 of fig1 . the lateral support arrangement lends itself to a relatively simple installation in that the support pad 35 which is attached to the ship &# 39 ; s structure can be installed once the tank is in its final position in the ship , by simply fitting it into contact with support pad 44 already attached to the tank , and welding support pad 35 to the ship &# 39 ; s structure . accordingly , no machining or measuring is necessary on the ship . fig1 , which shows the tank of fig1 with one - half of said tank removed , indicates how the internal closing caps 8 are arranged with respect to the cylindrical shells . the present invention being thus described , it will be obvious that the same may be varied in many ways . such variations are not be to be regarded as a departure from the spirit and scope of the invention , and all such modifications are intended to be included within the scope of the following claims .