Abstract: A method for manufacturing an integrated circuit device illustrates the preparation of the first surface of a circuit wafer including the placement of fine alignment indicia 34a outside the active chip area. A support wafer 50 is secured to the first surface of the circuit wafer 10 by an adhesive layer 58. The circuit wafer 10 is thinned. Openings 66 are photoshaped in the circuit wafer 10 using wafer flats 51 for alignment. The openings expose alignment indicia 34a which are relief images in the adhesive of the alignment pattern 34. The exposed surface of the circuit wafer 10 is photoshaped, using the indicia 34a for alignment, to define wafer segments 68 positioned over resistor doped regions 22.

Abstract: A U-shaped body (12) receives a plunger assembly (31) including a pair of push rods (30) which are rigidly secured together by a beam (32). Springs (36) normally bias the plunger assembly rearwardly so that the rod ends and slides (40) coupled thereto are normally positioned at terminal portions (18) at the end of the U-shaped body. Movement of plunger assembly beam (32) toward the body extends plates (46) of the slides outwardly against a connector half (20a) for separation thereof from its mating connector half (20) in a straight-line motion to prevent bending of any electrical contacts or breakage of the connector body. A strain relief (49) and the straight-line motion also reduces the possibility of damage to any electric or electronic devices coupled to either connector half.

Abstract: A liquid depth measuring device for measuring the depth of a liquid in a tank or other receptacle is disclosed. The device includes a vertically arranged outer housing member having a tubular central body portion, a tapered valve seat at the lower end of the body portion, and an annular sliding bearing member at the upper end of the body portion. The device further includes a tubular inner housing member mounted for longitudinal sliding movement through the bearing and extending in concentrically spaced relation within the outer housing member to form an annular space therebetween. A tapered valve member adapted for sealing engagement with the valve seat is carried at the lower end of the inner housing member, and a graduated measuring tape is arranged longitudinally within the inner housing member.

Abstract: A measuring device having a pair of pivotally moveable styli connected together by means of a potentiometer, for varying electrical resistance in accordance with the angular disposition between the styli. The measuring device further comprises a source of power in circuit with the potentiometer and a plurality of scale options comprising manual actuators for changing the electrical parameters in circuit with the potentiometer and a visual display device.

Abstract: An axial thrust bearing thickness measuring fixture for accurately comparing the axial thicknesses of two thrust bearing assemblies. The fixture includes a rigid base and a rigid plate. A clamping mechanism releasably interconnects the base and plate. It is operable to clamp the plate and base against opposite radial thrust surfaces of a bearing assembly, which might include one or more shims. Separation between the base and plate then is a function of the effective axial bearing assembly thickness. An indicator may be mounted between the base and plate to record differences in the measured axial bearing thickness.

Abstract: Offensive football formations at the beginning of plays can be accurately drawn on paper by the use of a unitary flat template having an array of apertures therein representative of all usual offensive players in their correct positions. By using a writing instrument in selected apertures, various offensive formations can be drawn with eleven players properly positioned to start offensive plays. Upon removal of the stencil from the paper, the execution of plays to completion can be conveniently diagramed. The device is ideal for use in the construction of team playbooks.

Abstract: A borehole survey method employs a first sensor for measuring angular rate, and a second sensor or sensors for sensing tilt, and a rotary drive for the first and second sensors, and includes the steps:(a) operating the drive and the first and second sensors at a first location in the borehole to determine the azimuthal direction of tilt of the borehole at such location,(b) then traveling the first and second sensors and the drive lengthwise of the borehole away from the location, and operating the drive and at least one of the first and second sensors during such traveling to determine changes in borehole alignment during such traveling.

Abstract: A tilt meter comprises two tilt sensors (110 and 110S, see FIG. 7) in a housing (105). Each sensor acts as two variable resistors (R.sub.s), which together with two fixed resistors (R.sub.F) form a Wheatstone bridge (25), driven by a square wave signal from a drive source (30). The output of the bridge is fed to an electronic circuit (35) which includes a synchronized switch (43) to cut out the spikes (50), which the bridge outputs at the transitions of the square wave. The output of the electronic circuit is a DC signal, whose amplitude indicates tilt magnitude and polarity indicates direction of tilt. The housing (105) is supported on a support surface (102S) by means of 15 legs (116, 117) threaded into nuts of the same metal, and which has a very low thermal coefficient of expansion.

Abstract: A drying apparatus employing adjustment baffles for cold air that is blown vertically upward from below a moving mesh belt, thereby achieving a uniform delivery of said cold air within a chamber heated by microwave energy.

Abstract: A method of and apparatus for vacuum drying a system, wherein the system is evacuated to effect vaporization of a liquid therein and facilitate its removal from the system, wherein at least one sample of the liquid is positioned within the system. The temperature of each sample and of the free space thereabove are monitored and the system is evacuated at a controlled rate so as to maintain the temperature of each sample at or above a pre-set temperature differential with respect to the free space thereinabove, as the temperature of the free space approaches the freezing point of the liquid until evaporation of all the samples is complete and the system is evacuated down to a practically achievable absolute pressure. The system is then isolated and the temperature of the system is allowed to rise, thereby causing any frozen liquid within the system to sublime or re-evaporate.

Abstract: A drying apparatus includes a cabinet, an open-ended drum having a horizontal axis disposed eccentrically inside of the cabinet so that an air path is defined between the wall of the cabinet and the peripheral surface of the drum, an opening with a door disposed in the central portion of the front panel of the cabinet and faced toward the open-end of the drum, an air inlet port provided on one side of the front panel communicating with the air path, an exhaust port provided on the other side of the front panel and communicating with the interior of the drum, and means housed in the cabinet for supplying hot air into the interior of the drum.

Abstract: A gas to solid contacting apparatus comprising a chamber, at least one solid inlet conduit opening into the chamber, at least one gas inlet conduit opening into the chamber, the gas inlet and outlet comprising superimposed conduits.

Abstract: Disclosed is an article of footwear such as a shoe having an inner sole and outer sole which delimit a vacant space of a predetermined height between them, the inner sole having a plurality of ventilating holes for communicating the vacant space with the interior of the shoe. A cushion member made of a light-weight, resilient material is disposed within the vacant space at the forward part of the shoe and has a plurality of elongated ribs spaced apart by a predetermined distance and extending to the rear portion of the vacant space. Each elongated rib has at least one recessed portion passing through the rib substantially laterally thereof to communicate with the spaces on either side of the rib. Compression and relaxation of the cushion member with the application and removal of the wearer's weight during walking creates a circulatory air flow to ventilate the interior of the article of footwear.

Abstract: This bowling shoe includes an upper portion and a lower portion attached to the upper portion. The inside edge of the lower portion projects outwardly from the line of attachment a conventional amount but the outside edge of the lower portion projects outwardly from the line of attachment a substantially greater amount than inside edge, to support the foot of the wearer during play. The outside edge is tapered to facilitate the support action.

Abstract: A shoe tap for tap dancing having first and second members pivotally connected by a pivot pin. The first member having a raised hemispherical protrusion with a first through-bore. The second member having a mating concave hemispherical recess coaxially disposed relative to a second through-bore. The pivot pin being of a diameter less than the first and second through-bore and extending therethrough and thereby not inhibiting the relative motion of the pivotally mounted second member to the first member affixed to the dancer's shoe.

Abstract: The present invention relates to a peat machine for connection to a tractor or a corresponding power source. The piece peat machine is provided with a digging means for digging peat and a pressure screw for digged peat. In order to improve the production capacity and to reduce the power demand, the pressure screw is conically shaped so that its diameter diminishes towards the outlet nozzles. In addition, the thread of the pressure screw is, at the end facing the digging means, substantially at right angles to the shaft of the screw or inclined forwards towards the outlet nozzles. At the outlet nozzles, the thread is inclined backwards towards the digging means.

Abstract: The disclosed film viewer comprises a box with a bottom and an inclined top having a diffusion plate fitted therein, a light source disposed in the box, and a number of reflectors distributed on the inner surface of the box so as to reflect light beams from the light source in such a manner that uniform brightness is provided throughout the entire surface of the diffusion plate.

Abstract: An improved identification locket having magnifying lens, a case, a frame for retaining a transparent transcript and means for opening and closing the case, also includes a support for maintaining the lens at a fixed distance from the frame and for preventing movement between the cover and frame in the open position. The support includes a first and second slotted arm attached to a first and second slide pin; each arm having a keeper for lockingly retaining the slide pin when the locket is in the open position.

Abstract: A removable cartridge magazine for firearms adapted to engage the firing chamber of a firearm comprising an elongated housing, a first gear rotatably mounted in one end of the housing adjacent the portion of the housing that engages the firing chamber of the firearm, a second gear mounted at the other end of the housing, an endless belt encircling the gears and engagable therewith whereby rotation of said gears rotates said belt, the belt being spaced inwardly from the inner wall of the housing, a plurality of spaced shell receiving compartments mounted along the outer periphery of said belt adjacent the inner wall of the housing, each compartment being an elongated groove extending longitudinally across the outer surface of the belt adjacent the inner wall of the housing in a direction traverse to the direction of movement of the belt.

Abstract: Disclosed is a revolver with a cylinder having an elevated number (e.g. 12) of cartridge chambers, this cylinder being held in a frame formed in part by a pivotable yoke on which the cylinder can be swung out laterally for reloading. The remainder of the frame is integral with a trigger guard which is located behind the cylinder and, along with other structural elements, is bracketed by a sheet-metal jacket of inverted-U shape forming the body of the firearm. A pistol grip attached to that body contains a compression spring which is coupled to the hammer of the firing mechanism and is repressible by the trigger or an independent lever to cock the hammer for double-action or single-action firing. A loader, comprising two hingedly interconnected disks juxtaposable to bracket the end flanges of a set of cartridges between them, is insertable into a clearance between the rear face of a cylinder and a stationary shield fastened to the frame.

Abstract: A hammer assembly for a side hammer percussion lock is comprised of a hammer which is displaceable relative to the firearm from its normal operative position to a safety position where it cannot be brought into contact with a percussion cap placed on the firearm. In one embodiment of the invention the hammer is displaced by rotating it about an axis which is perpendicular to the axis about which the hammer is rotated between its cocked and firing positions. In another embodiment of the invention the hammer is displaced to its safety position by being slidably translated relative to the firearm. In the rotating embodiment, detents are provided for fixing the hammer against inadvertent movement from its desired position. In the sliding embodiment a lock is provided to prevent movement of the hammer from either its normal or safety position without first releasing the lock. A cam is provided in both embodiments to lift the hammer slightly off of the percussion cap when it is moved out of its normal position.

Abstract: An outrigger fishing rod holder for mounting in or on the hull of a fishing vessel for holding a fishing rod in a fixed position until a catch is made. The device comprises a tubular member for fixedly holding the fishing rod and the tubular member in turn is pivotedly mounted in a generally U shaped holding bracket. The U shaped member in turn has a tapered mounting bracket attached to it for securing same to a mounting plate on or in the hull of the fishing vessel. The U shaped supporting bracket has a semicircular cut out portion which allows the tubular member to pivot after a catch has been made.

Abstract: A dual purpose fishing lure system composed of a bent strip of metal having a hole at each end and one elongated in the mid-portion with a hook attached to the strip of metal. The lure is designed so that either end may be attached to a towing fishing line to provide two different types of action of the fishing lure. When the towing line and hook are attached at the same end and the hook passes through the elongated hole on the lure, the rear portion of the lure will spin, creating the appearance of a fluttering tail action. When the towing line is attached to the other end of the lure and the hook is removed from the central hole and allowed to drag behind while, the lure will move through the water simulating the wiggling, wobbling, darting action of a live baitfish. Regardless of where the towing line is attached, one hole is left open through which water may pass to produce fish attracting sound vibrations.

Abstract: A wire form shape is presented which may be used in the manufacture of a fishing lure as both a line tie means and a hook attachment means. The wire form includes a 270.degree. loop at one end which cooperates with assembly locating pins within a fishing lure body and a 180.degree. loop near the other end of the wire which forms a means to suspend hooks or tie a line.

Abstract: A plastic worm fishing lure having a double action inner and outer skirt. The skirt is attached at the gland portion of the worm body by a tie binding and has a rearwardly extending inner skirt and a longer forwardly extending outer skirt which doubles back to the rear over the inner skirt as the lure is pulled through the water. The plastic worm body may be provided with a molded in-situ sealed buoyant sound chamber partially filled with shot which produces sound vibrations as the lure is moved through the water. The sound chamber is located at the head section of the worm body to provide buoyancy to lift the head end with respect to the tail end when the lure is immersed in the water.

Abstract: A fish hook holder comprises a base member having a first planar surface with a series of flat recesses therein which open to a first edge of said base. A cover is bonded to said base to form hook retaining compartments in said recesses, the hooks fitting snugly between the floors of the respective recesses and the cover and being retained by resilient nubs extending above the floors. A protected line severing blade may be provided in one end of the holder which is shaped like a fish for convenience in packaging and use.

Abstract: The trap has a ring shaped passage with a door which, when opened, extends into the passage so that a mouse can only enter the passage in one direction. A bait trail in the passage extends around to the back side of the door where it can be pushed closed by a mouse, or released by the mouse and closed by a spring. Magnetic or spring means are disclosed for holding the door in the closed position. An attractant dispenser is provided for dispensing fresh attractant near the back side of the door when the trap is to be used.

Abstract: An electrically self-powered miniature toy vehicle having three or more driven axles, and being capable of climbing over rough terrain and obstacles as well as up steep inclines. In a preferred form, the vehicle in the form of the cab of an 18-wheeler truck is only slightly longer than two AA penlight batteries placed end-to-end and the chassis is less than twice the width of such batteries. The vehicle has a small electric motor with a double-ended shaft and a gearing system which drives the three or more axles. The motor and gearing system are located along one side of the chassis while the batteries are located along the other side of the chassis. The batteries are located approximately the same height as the wheels of the vehicle, and laterally adjacent to the motor. The frame, the motor and the batteries do not protrude any appreciable distance below the level of the axles in the area between the front and rear wheel. In a preferred form there is one front wheel axle and two rear wheel axles.

Abstract: A floating hydroponic apparatus is provided along with a hydroponic system using the hydroponic apparatus. The floating hydroponic apparatus has a floating hydroponic tray having a floating base portion and a tray portion. The floating base portion is made of a lightweight cement and has floating perimeter walls along with a polymer screen attached between the floating base portion and the tray portion. The floating base portion and tray portion form a plurality of openings therethrough for the passage of liquid. An alkaline resistant coating is applied to at least a portion of the tray. The tray portion is filled with a soil mixture supported by the polymer screen so that plants can be grown in the soil in the trays while the trays are floating upon a liquid reservoir. The trays can be used in conjunction with a hydroponic system having pools with specially designed lightweight concrete walls forming a habitat for marine life.

Abstract: A wall mountable safety hatch comprising a pair of telescopically engagable door frames that insert through a conventional studded wall forming an emergency exit. A pair of flush mounted doors insert into the wall mounted frame and are held in proper alignment by a seat belt type fastener. Upon releasing the conventional seat belt clasp, the door falls from the frame exposing the emergency escape hatchway.

Abstract: In a window lifting mechanism 10 for motor vehicles, with an engagement member 16 which engages at a window pane, a slide member 24 which is connected with the engagement member and is supported to be slidable at a guide rail 26, and a cable drive 12 to move the engagement member 16 along the guide rail 26, the engagement member 16 is supported at the slide member 24 so as to be slidable in the longitudinal direction X of the guide rail 26, i.e. simply by attaching the engagement member 16 at a bearing part which in turn is supported to be slidable at the slide member 24 in the longitudinal direction X. With this simple arrangement an increase in the lift of the window lifting mechanism at a specified length c of the guide rail 26 is achieved, while maintaining the mechanical stability of the window lifting mechanism with respect to tilting motions of the window pane which lie in the plane of the window pane. Preferably a steel band loop 44 is used as the bearing part.

Abstract: A gate assembly including a gate portion, a gate support portion and a gate connecting portion; the gate portion including vertical end braces connecting and being affixed to the ends of horizontal board members and a vertical center brace, diagonal braces extending between the lower ends of the vertical end braces and the upper end of the vertical center brace; the gate support portion including a fixed vertical support column with a generally circular cross section, a rotatable anchor collar disposed adjacent the top of the support column, the collar surrounding the upstanding support column and being spaced therefrom in a generally horizontal plane, bearings disposed between the support column and the collar, U-shaped hinges disposed around the upstanding support column and freely rotatable with respect thereto, the free ends of the hinges extending along and being affixed to opposite ends of the gate portion adjacent one end thereof; the gate connecting portion including a bracket affixed along the length

Abstract: A double glazing arrangement has at least one pane mounted between two opposed vertical channels and arranged for both vertical sliding movement within the confines of the channels without the provision of a counterbalancing system and movement in at least one lateral direction for removal of the pane without any initial dismantling of the arrangement. Releasable catches are provided which are for both holding the pane in a plurality of raised positions and preventing lateral movement of the pane. The arrangement is particularly advantageous for a pane of transparent acrylic material.

Abstract: An apparatus for the manufacture of lens-like articles and the like, in which two work holders are provided in a manner to be movable along a common center axis and rotatable thereabout and machining means is provided for surfacing a work or work-piece held by each of the work holders.A method for the manufacture of lens-like articles and the like in which after machining one surface of the work held by one of the work holders, the work is transferred to the other work holder without changing the center line of machining and subjected to machining of the other surface, thereafter being subjected to edge planing.Lens-like articles and the like which are obtained by the manufacturing method.

Abstract: A method of and machine for point grinding drills by supporting the drill to be pointed in a relatively fixed position and thereafter moving the drill and a bevelled grinding surface relative to each other while rotating the drill about its axis, and by selecting a point of grinding engagement with the bevelled grinding surface a desired lip relief angle may be ground on the drill tip along with a chisel edge angle and a point angle.

Abstract: An improved grinding wheel support arrangement in a grinding machine. The support arrangement includes a support frame on which a support member is pivotally mounted at one of its free ends. A support leg is pivotally mounted on the support member at the other free end. A grinding wheel shaft supporting a grinding wheel is rotatable on the support leg. At least two separate adjusting means are operatively connected to the support frame; a first adjusting means being directly connected to the support frame and the second adjusting means being connected to the support leg to adjust the position of the grinding wheel relative to the support frame. The two separate adjusting means act in the plane of the grinding wheel in mutually intersecting directions.

Abstract: The machine comprises a support surface for a reference surface on the body of the workpiece, and a device for fixing the body on the support surface and releasing the body. A withdrawable device is provided for angularly positioning the blank on the support surface. The device comprises a V-shaped recess facing the support surface. The machine permits a center-less grinding of cylindrical surfaces in overhanging relation and in particular trunnions of tripods for homokinetic joints.

Abstract: An electrically driven knife whetting machine including an electric motor having a rotating shaft, the electric motor being contained in a motor housing with the shaft extending out of the motor housing. A grindstone rotating assembly is securely mounted on the shaft, the assembly including a grindstone mounted on a grindstone holder with the grindstone having a grinding surface. A cylindrical upper cover is securely mounted on the motor housing. A knife blade regulating and guiding member is cylindrically shaped like an upside-down cup for receiving the grindstone therein, the cup having a knife blade guiding opening of a given angle and size provided in a cylindrical wall thereof, with the guiding opening being disposed above the grindstone. A spring member for elastically moving the cup relative to the upper cover so that the guiding opening can be moved up and down with respect to the grindstone, where the cup is prevented from being laterally rotated with respect to the upper cover.

Abstract: An adapter which mounts on the spindle of a surface grinder spindle to support a small grinding wheel having a relatively small shank.

Abstract: A chucking method and apparatus for processing a lens blank in a manner requiring only a single mounting of the blank to an associated lens block. The lens block is mounted to the convex lens blank surface by a hot melt type of adhesive so as to extend outwardly thereof substantially coaxial with the lens blank frame center axis. The lens blank and lens block are releasably mounted in a chuck assembly associated with lens surface generating apparatus such that a desired optical center axis in the lens blank and the tailstock of the generating apparatus are coaxial. The chuck includes means for selectively rotating and/or canting the lens blank relative to the tailstock to accommodate desired axis and prism settings as prescribed for the finished lens. Following generation of the desired optical characteristics in the lens blank, additional operations are performed thereon for producing a finished optical lens while the lens block remains affixed thereto.

Abstract: A universal grinding bar adapted to be connected to a standardized, quick-change tool holder can be devised for use with conventional engine lathes, milling machines and the like and used as a standardized tool without the limitations of direct coupling to the drive of the engine lathe or milling machine. The universal grinding bar includes a modular delivery tube of selected shape and length and a modular turbine housing connected to the delivery tube and including a selected one of a plurality of pneumatic motors characterized by different operating speeds. Pressurized air is coupled through the end of the delivery tube distal from the turbine housing and is delivered to the pneumatic motor through a pressure tube. The spent air is then returned through a metering plate between the turbine housing delivery tube through an internal bore within the delivery tube to exhaust ports at the distal end. The delivery tube is of such diameter to allow connection to a conventional quick-change tool holder.

Abstract: Building system in which the supporting elements are formed by partitions or plates (1-16) one group of plates (1,2,3,4) being placed in spaced apart parallel vertical planes with all plates (1,2,3,4) of said group having the same width in horizontal direction which width corresponds to the width of a cupboard the plates (1,2,3,4) of said group being placed between at least two vertical plates (9,10) which extend perpendicular to the plates of the first group. Preferably a third plate (18) or group of plates is placed in a horizontal plane between the vertical plates.

Abstract: A skylight for mounting on the roof structure of a building to allow sunlight and the like to enter the interior of the building. The skylight includes, in general, a frame for being mounted on the roof structure, a first transparent plate for being supported on an upper flange member of the frame, a second transparent plate for being supported from an intermediate flange member of the frame, a cap for securing the first plate to the frame, and a lock for locking the cap and frame together.

Abstract: This invention concerns a false ceiling element consisting of a strip of thin flexible material, folded generally in a zig-zag manner transversely to its length and hung from at least one support for longitudinal sliding thereon, characterized in that the surfaces of the folds of this strip are connected to one another by at least one flexible element.

Abstract: A porch and stairway assembly for a mobile home, or the like, which may be readily assembled or disassembled, and which comprises a porch section, a handrail section and a stairway section, the sections having cooperating interlocking bracket members for sliding and pivoting engagement to readily lock the sections in the assembled relationship and unlock the sections when the porch and stairway assembly is not needed. The entire assembly may be secured together with a minimum number of securing elements, such as bolts, or the like, thus greatly facilitating both the installation and removal of the assembly.

Abstract: Multi-wall devices embodying two or more spaced members arranged to provide an enclosed space therebetween for controlling the transmission of energy through the members for the purpose of capturing, storing and releasing energy.

Abstract: A building panel of wood composite material includes inner and outer faces outlined by opposite ends and upper and lower edges. The panels are adapted to be placed end-to-end in courses or rows arranged in parallel to extend upwardly from a lower edge or eave to cover a building wall or roof structure. Each panel includes an outer face having a lower portion of substantial surface area adapted for exposure to the weather and an upper portion of relatively smaller surface adapted to underlie one or more panels in a next higher course laid in overlapping relation therewith. A large lower portion of the outer face is formed with a surface embossed to resemble a plurality of individual shingle elements positioned in side-by-side relation. Grooves are formed in the outer face of the panel between adjacent shingle elements and each groove tapers from a minimum depth adjacent the upper portion of the outer face to a maximum or greater depth adjacent the lower edge of the panel.

Abstract: A multi-stage extendable tower for controlled elevated support and positioning of workmen and equipment having a plurality of telescoping frame sections that may be raised from a collapsed nested position to a partially or fully extended position. Functionally positioned and interconnected between each adjacent frame section is at least one heavy-duty coiled spring whose potential energy stored in torsion provides sufficient lifting force to overcome the weight of the above frame members, workmen and equipment. Both manual and motorized means are disclosed and claimed for effecting compression and renesting of the frame members.

Abstract: The present invention relates to a combination glass spacer and plastic film holder for installation in an insulated glass panel. A channel or opening for receiving an edge of a thin plastic sheet or film is integrally formed at the upper or topside of a somewhat rectangular shaped longitudinal tubular member.

Abstract: The dimensions of the blocks or bricks are, first, derived from the side lengths a, b of the tiles and, second, from the thickness d of the corner tiles, whereby an amount (a/2)-d, or (b/2)-d is obtained for the wall thickness of the blocks. The two-shell structure as well as the usual staggered arrangement by half the tile length provides a sequence of blocks of the following lengths: (a/2)-d, a/2, a-d, a, (3a/2)-d, 3a/2, 2a-d, 2a, etc. A further sequence of blocks of the following heights is obtained: (b/2)-d, b/2, b-d, b, (3b/2)-d, 3b/2, 2b-d, 2b, etc. Further sequences in respect of height and length are obtained from the two basic sequences, each smallest member being a member of a basic sequence. In a preferred embodiment, the tiles have a square visible face and the thickness a/4. Hence, the blocks have the same wall thickness and the length and heights a/4, a/2, 3a/4, a, 5a/4, 3a/2, 7a/4, 2a, etc.