Abstract: A method and apparatus for the removal of condensate from a cylinder, in particular a cylinder for drying paper by means of steam supplied under pressure to the interior of the cylinder via a first conduit. The steam, partially condensed to water, is removed from the cylinder through a second conduit. Optimum discharge of condensate is achieved, even at higher cylinder speeds by separating the fluid in the second conduit into a gaseous component and a liquid component, measuring the quantity of the gaseous component, and keeping the same constant by control means.

Abstract: A shrink tunnel, a gate for opening and closing the egress opening of the shrink tunnel, prime mover means for moving the gate, and sensing means operatively connected to the prime mover means to open the gate just prior to exit of an article from the shrink tunnel and to close the gate after the product has exited therefrom.

Abstract: An apparatus for automatically ironing textile articles and the like comprises a box-like structure provided with bellows doors, which are mechanically driven to open and closed positions. In the central portion of the bellows doors, an upright is pivoted which is also mechanically driven for alternately rotating through a 180.degree. angle, and bearing two radially extending arms provided for supporting the textile articles to be ironed.

Abstract: A flying insect trap has a hollow body with a bottom portion. A plurality of legs are connected to said body and this body has an aperture in its bottom portion. A pair of transparent baffles are mounted inside the body and extend upwardly and converge to form a small opening. The top is transparent to let light in and attract the fly to the top where it is caught. The body is shaped and has a plurality of legs to resemble an animal whereby the body provides a visual lure.

Abstract: A novel coating for crop seeds is disclosed which serves to delay germination of the seeds after planting thereof for significant periods of time (such as over the winter months), and thereafter allows germination and plant development in the normal manner. The preferred seed coatings include a relatively rigid, dried residue of a synthetic resin (e.g., an epoxide) which is filled with a material such as a hydrate former which slowly reacts with moisture from the earth and expands, so that the resin coating will rupture and allow seed germination when soil and climatic conditions are conducive to plant growth. It has also been discovered that a preferred precoating comprising methyl cellulose serves to enhance plant growth and hardiness, particularly in the period shortly after emergence.

Abstract: The present invention relates to a hydroponic culture method for animal food, regrouping semi-automatically and in a single device, five germinating operations, on superimposed trays, namely, propagating the seeds on the trays, soaking said seed directly on said trays, programmed irrigating of the seeds and roots, heating by way of electrical elements incorporated in the trays, and if necessary injecting nutrient solutions by quantity-controlling pumps.The invention further relates to the device usable for carrying out said method.

Abstract: This invention is a method and an apparatus by which a barrier is automatically placed before partially opened doors, which barrier is automatically removed when the door is fully opened and safe for travel. The invention includes means to detect when the door is fully opened and thereupon to activate barrier removal means, together with barrier placement means automatically activated at any time when the door is not fully opened.

Abstract: Apparatus for polishing a workpiece wherein an oversize resilient elastomeric polishing die has injector ports through which a viscous or elastic polishing medium is injected. The workpiece is mounted in vertical working alignment with respect to the polishing die. The die and workpiece are moved relative to one another in a horizontal oscillatory rotary motion as they are brought together in the vertical direction such that the workpiece surfaces are polished.

Abstract: This invention is concerned with ultra precise apparatus for forming a complex profiled face on a diamond tool blank. The apparatus comprises an abrading device in the form of a grinding wheel and a spindle means which includes a journal for supporting the grinding wheel. This journal is rotatably supported upon an air bearing. A platform, supported for rotation about a vertical pivot axis, is also supported for displacement in a horizontal plane along an axis perpendicular to the pivot axis. An air bearing supports the platform for rotation about the pivot axis while another air bearing supports the platform for displacement in the horizontal plane perpendicular to that axis. A tool chuck is mounted upon the platform and serves to present the tool blank to the grinding wheel. A cam, mounted adjacent to the platform, is provided with a surface whose contour is related to the complex profiled face to be formed on the tool blank.

Abstract: In belt chamfering machines, the glass sheet being machined is gripped and conveyed during the machining (chamfering) of its edge between two facing portions of two belts. The rear belt extends downwards more than the front belt as it has to provide a support for the sheet at or in proximity to the edge being machined. Small sheets cannot be machined by known machines of this type because they would not be adequately gripped between the two belts. To obviate this drawback, the invention provides for the rear belt to be able to be adjusted in height so as to vary the downward projection of said belt relative to the front belt. At the same time, the position of the conveyors on which the sheets rest before and after machining can be adjusted to the same degree.

Abstract: A computer-controlled lens generating arrangement (1) has a calibration gauge (14) mountable on a lens chuck (28) and moveable into a calibration position for detecting a worn or eroded condition of a tool (18). When a worn or eroded condition of tool (18) is detected, data are provided to a computer (60) which recomputes positioning data for the chuck (28), and repositioning of the chuck (28), as well as the angle of the cutting tool (18), takes place.

Abstract: Two rolling bands, meaning windable and unwindable bands, are affixed to a carriage or slide which is reciprocatingly movable along a guideway. The rolling bands are each arranged to be rolled-off from a respective drum journaled at each end of the guideway. A respective wheel is rigidly coupled to each one of the drums. Two belts interconnected by a tension spring are each arranged to be wound-up upon a respective one of the wheels in opposite direction to the winding direction of the rolling band on the related drum. Without itself being subjected to substantial loading and elongation differences, the tension spring continuously holds both of the rolling bands under tension.

Abstract: An abrading tool for finishing surfaces comprising, in one embodiment (5), one or more sanding fingers (20) keyed to a rotatable disc (15). A biasing spring (65), disposed proximate each sanding finger (20), tends to force the sanding fingers (20) towards the surface to be finished by biasing the sanding fingers (20) towards a position which is vertical or substantially perpendicular to the disc (15).

Abstract: A ceiling module includes a ceiling-defining sheet of material and an overlay spaced above and parallel with the ceiling-defining sheet. The overlay is secured to the ceiling-defining sheet along the periphery of the ceiling-defining sheet and also at positions spaced inwardly from the periphery to support the ceiling-defining sheet.

Abstract: Office partition panels are mounted on cylindrical connector posts. The posts have tongues or grooves running along parts or all of their length which match with corresponding grooves or tongues or locking pieces readily affixed to or integral with the edges of the panels to hold the panels securely in place.

Abstract: An automatic electric cable passage closure and sealing device, for positioning in an opening in a structure such as a floor or wall, etc., for passing or connecting a cable or cables and cable conduits therethrough, the device automatically expanding and sealing itself and the cables and cable conduits in the structural opening on occurrence of excess heat or fire. The device comprises a hollow conducting casing to be positioned in a cable or conduit passage in the structure, said casing having novel means effectuating automatic movement and expansion of intumescing, fire retarding, means on occurrence of fire or highly elevated temperatures, said intumescing means pressing through the cables insulation and onto the conductor wires interiorly of the cables.

Abstract: A knock-down room divider construction comprises a series of separate posts and panels which are mutually releasably engageable. Each post comprises a rigid core member covered on its outer surface with a fastening fabric which is complementary to a second fastening fabric on the vertical edge of a panel section. By having the panels and supporting posts as separate units, a lighter construction is possible and there is a greater flexibility in geometry and arrangement of the room partition.

Abstract: A roofing system, comprising a roof; a plurality of elongated roofing members on said roof, each said member comprising an elongated, three-ply laminate body portion and integral opposed, first and second longitudinally extending edge portions, said first edge portion comprising a one-ply cover means and a two-ply body means and said second edge portion comprising said three-ply laminate; said three-ply second edge portion of a said member being between said cover means and said two-ply body means of an adjacent said member, and means for fastening a said second edge portion of one member and its associated body means of an adjacent member to said roof.

Abstract: Mounting means for thermal insulation blocks or modules are described. The means comprises a rounded member adapted to fit into and cooperate with a C-shaped channel member attached to the block, with the rounded member itself being secured by a securing member to the wall of a furnace or like device. The mounting member allows the block to be easily secured to the wall even in locations of limited access.

Abstract: A composite, pre-stressed structural member comprised of concrete and a lower metal support member, and method for forming and pre-stressing the same. The metal support member and a concrete mold are connected for parallel deflection with the support member uppermost and shear-connectors extending into the mold. The connected mold and support member are supported for deflection and concrete is poured into the mold and allowed to harden. During hardening of the concrete the mold and support member are deflected by the weight of the concrete, mold and support member, pre-stressing the support member. Upon hardening of the concrete and inverting to a concrete-uppermost position, a composite, pre-stressed structural member is provided.

Abstract: A portable packaging machine for making a continuous ribbon of interconnected packets with each packet containing one or more pills or capsules. The machine has a unique single frame structure whereby the machine weighs less than fifty pounds to facilitate shipping, particularly in those instances where a fifty pound maximum is a factor. The frame is of open construction to provide increased air circulation. A message is imprinted on each packet by means of a stencil having a special stamp pad and ink to provide a clear imprinted impression after an unusually high number of impressions.

Abstract: A bagging device for transferring material from a first chamber through an opening in a wall to a second chamber includes an outer housing communicating with the opening and having proximal and distal ends relative to the wall. An inner housing having proximal and distal ends corresponding to those of the outer housing is mounted in a concentrically spaced, sealed manner with respect to the distal end of the outer housing. The inner and outer housings and mounting means therebetween define an annular chamber, closed at its distal end and open at its proximal end, in which a pliable tube is slidably positioned in sealed engagement with the housings. The pliable tube includes a sealed end positioned adjacent the proximal end of the inner housing so as to maintain isolation between the first and second chambers.

Abstract: A lawn mower including a blade housing supporting a prime mover which drives a cutter blade. The prime mover causes rotation of a drive shaft and a clutch driven by the drive shaft is engagable and disengagable with the cutter blade. A handle is connected to the housing and a dead man control is pivotally attached to the handle. The lawn mower further includes an arrangement operable to permit the engagement and disengagement of the clutch means by the pivotal movement of the dead man control. This arrangement includes a flexible member connecting the dead man control and the clutch and an arrangement restricting a substantial portion of the flexible member to a predetermined path along the handle. The restricting arrangement includes a pulley rotatably attached to the handle between the dead man control and the housing and the flexible member is guided around the pulley.

Abstract: An attachment for the snout of a combine includes a plate which is disposed above the snout and is inclined upwardly and rearwardly at an angle greater than the angle of the upper surface of the snout to provide a steeper surface for engaging and lifting a down crop. The plate extends above the conventional ear saver which thereby may remain in place to prevent corn ears from being ejected from the combine. The forward end of the plate is fastened to the snout and the rear end is supported on the ear saver by a sliding connection which permits the forward part of the snout to tilt up as it encounters mounds of earth and the like.

Abstract: The driving device for the twisting head of an SZ stranding machine assures short switching times with little equipment even for a multi-step change of the rotary motion by associating with one or both magnetic clutches of the twisting head either one driving shaft rotating at changing speed, or at least two driving shafts revolving at constant speed and each having a magnetic clutch for coupling rotation to the twisting head clutch.

Abstract: A machine for the manufacture of chains of the "rope chain" type for the goldsmithery industry, in which each link is taken from a spiral of wire by means of one or more cuts tangential to the internal profile of the winding. The cuts can be simultaneous or consecutive. The cutting unit includes a pair of blades, the cutting plane of which is adjustable with respect to horizontal so that it can be perpendicular to the coil winding to be cut; it also oscillates between two cutting positions in order to obtain separation of the link with two consecutive cuts in correspondence to two intermittent, 180.degree. one-way rotations of the coil. For chain-linking, a calibrated passage with a decreasing section is provided, in which the take-up unit, after having united a link to those already joined, forces the chain to advance, producing closure of the links with partial overlapping of their contoured extremities.

Abstract: Methods and apparatus for improving the thrust specific fuel consumption (TSFC) of a gas turbine engine employing an exterior active clearance control system are disclosed.The pressure within the nacelle compartment to which active clearance control air is discharged is operated under altitude cruise conditions at a level on the order of one to two and one-half pounds per square inch (1-21/2 psi) above the ambient atmosphere. Flow discharging from the nacelle is directed through an aft facing vent nozzle for purposes of thrust recovery.

Abstract: A gas turbine engine air intake comprises an enlarged center body positioned upstream of the engine air inlet. The center body is provided with a drain so that in operation water particles impacting and flowing across the surface of the center body are directed into the interior of the center body. From there the water is drained into a by-pass duct which exhausts the water into the exhaust efflux of the engine to which the intake is attached.

Abstract: Steam power plant, including a steam turbine having a high pressure section with an exhaust steam outlet, a steam generator having a live steam side connected upstream of the high pressure section of the steam turbine, the steam generator having a combustion chamber and a convection space formed therein, an intermediate superheater heating surface having an outlet and having an inlet being connected to the exhaust steam outlet of the high pressure section of the steam turbine, a device for applying combustion air to the combustion chamber of the steam generator, and a device disposed at the outlet of the intermediate superheater heating surface for regulating steam temperature thereat, the regulating device including a nozzle terminating in the convection space of the steam generator between the combustion chamber and the intermediate superheater heating surface.

Abstract: Fuel flow to the burner (10) of a gas turbine engine (15) is turned on and off by a minimum pressure valve (60) controlled by a fluid pressure operated sequence valve (110). The sequence valve includes a valve element (125) set by the pressurization thereof with fuel discharged from a pump (35). The setting of the sequence valve element (125) is maintained by a fluid latch also energized by fuel discharged from the pump whereby no complex linkages or electric motors are required for the setting of the sequence valve and the maintenance of such setting.

Abstract: This invention provides apparatus for use in a drive transmission system comprising a pump adapted to perform work on a medium and means repetitively and automatically to unload the pump. When connected with a flywheel driven by a prime mover an embodiment alternately performs work and then is unloaded to permit acceleration of the flywheel. In use in a driven transmission system there is provided a flywheel driven by an engine, a pump driven by the flywheel, powered by the pump, and means repetitively to unload the pump permitting the engine to accelerate the flywheel and compensation means to power the hydraulic motor while the pump is unloaded. The pump is preferably a rotary positive displacement pump having relief galleries eliminating the seal between pumping elements driving each cycle.

Abstract: An axial piston-type transmission in which a group of axially displaced pump pistons, that move in a cylinder block rotated by an input shaft, slidably engage one surface of a swash plate that rotates an output shaft. A group of axially displaced motor pistons, that move in a stationary cylinder block, slidably engage an opposite surface of the swash plate so that the plate is squeezed between the two groups of pistons. The swash plate is pivotally attached to the output shaft so that the angles between the two surfaces and the axis of rotation of the swash plate can be adjusted. The pump pistons and motor pistons are hydraulically connected in pairs. A rotary valve driven by the output shaft connects half the pump cylinders together hydraulically to form an output port and the other half together to form an input port.

Abstract: In an engine comprising a primary engine unit 1 and an auxiliary engine unit 2, water jackets 44, 47 of the primary engine unit are connected to water jackets 46, 48 of the auxiliary engine unit and to a radiator 43 in series, and bypasses 52, 55 are connected to respective water jackets.

Abstract: The circuit arrangement includes a first voltage divider including a temperature sensitive resistance 18 and resistor R1 which feed an analog signal through line 30 to comparators CP1-4, which also receive reference voltages from a second voltage divider comprising R2-5. CP1 goes high with a falling temperature of 26.degree. F. or lower, CP2 goes high when the temperature falls below 22.degree. F. and CP3 goes high when the temperature falls below 18.degree. F. A first timer 20 is turned on when any of the comparators are turned on and counts pulses from an R-C circuit including R8-11 and C1. Whether R8 and 9 are in the oscillator circuit depends upon whether the bilateral switches S2 and S3 controlled by the comparator CP2 and CP3 have shunted them out. Accordingly, the counting is speeded up as the temperature drops.

Abstract: An absorption cold and warm water system utilizing solar heat includes a low temperature heat generator using as a heating source low temperature warm water obtained by heating water by the solar heat, a high temperature generator using an ancillary heat source as a heating source when the system runs short of the solar heat, and a low temperature generator. The cold and warm water system is provided with an operation device operative, when the cold and warm water system is in condition in which refrigerating and heating outputs can be provided by using the low temperature warm water, to allow the low temperature warm water to be continuously fed to the cold and warm water system and to control the volume of a solution and a refrigerant in circulation in accordance with temperatures of the cold and warm water, to thereby store the solar heat in the cold and warm water system.

Abstract: A reversible mode heating and cooling system comprises a conventional reversible heat pump unit having a compressor, a reversible valve, an indoor heat exchanger in heat exchange relationship with indoor ambient air, refrigerant expansion means and an outdoor heat exchanger in heat exchange relationship with outdoor ambient air, and operatively associated therewith, an auxiliary heat exchanger in heat exchange relationship with a heat exchange fluid for enhancing the capacity and efficiency of the system to evaporate refrigerant during the heating mode and to condense refrigerant during the cooling mode. The auxiliary heat exchanger is arranged for selective parallel or simultaneous parallel and series flow of refrigerant through the auxiliary heat exchanger and the outdoor heat exchanger to enhance the heating efficiency of the system at very low outdoor ambient temperatures.

Abstract: A method of operating an air conditioning system including a refrigeration circuit having a compressor and a thermostat for sensing heating and cooling needs together with an indoor fan is disclosed. The indoor fan operation is controlled based upon a microprocessor control remembering whether or not the unit was in continuous fan operation prior to the compressor operating to satisfy a heating or cooling need. Through the setting of a flag the microprocessor remembers the previous inputs such that operation of the fan may be controlled regardless of the condition of the compressor especially as concerns operation of the fan when the compressor is prevented from operating due to a safety, overload or timed off condition.

Abstract: An air conditioning system with incorporated evaporative cooling apparatus dapted to sequentially pass compressed air from a compressor through a heat exchanger and expansion cooling turbine and into an enclosure. A condensate extractor is interposed downstream of the expansion cooling turbine and located above the heat exchanger. A nozzle is mounted to the heat exchanger and connected via a water conduit to the condensate extractor so that gravity delivers extracted condensate to the nozzle. The nozzle communicates via an air conduit with the compressor so that compressed air disperses the extracted condensate through the nozzle to impinge upon the heat exchanger thereby effectuating evaporative cooling.

Abstract: An improved ring construction suitable for rings, bracelets and similar articles of jewelry, in which a metallic braided decorative strip is underpinned to the outer surface of the ring so that the end and side edgings are shielded from accidental contact during wearing by a user. The ends of the braided strip are enclosed beneath a covering lip forming a part of the ring at each end thereof, while the side edges are covered by planar circular plates soldered to the body of the ring.

Abstract: Described is a foulard machine with the minimum possible application of liquor. For this purpose, a wiper is held against the circumference of an enlacing roller by means of forces of magnetic repulsion. The wiper has a plurality of recesses or indents next to one another which act to convey the liquor. Any out-of-rounds of the enlacing roller are compensated for by the forces of magnetic repulsion so that the wiper abuts against the circumference of the roller uniformly over its entire length.

Abstract: First and second stop bodies are arranged to clamp around the lever of a pedal which operates an apparatus. When the stop bodies are locked in place, the pedal cannot be operated and, thus, the apparatus is restrained.

Abstract: A universal boltworks mechanism is compatible for use with any of a range of shapes and sizes of safe door and is alternatively enclosed in an easily fabricated centrally located bore on the interior surface of the safe door or in a pan enclosure which is easily welded to the interior of the safe door. The mechanism particularly includes a universal cam member which is configured such that it may be used without adaptation with any of said shapes and sizes of safe door alternatively driving three bolt driving structures of a first configuration on one side thereof and four bolt driving structures of a second configuration on the other side thereof. The universal boltworks mechanism is also provided with a bolt inhibitor which inhibits unlocking movement of each bolt whenever a breakaway portion of the mounting enclosure cover plate has been broken away in response to tampering forces in excess of a predetermined amount.

Abstract: A portable sheet bending brake comprising a first member defining a clamping surface extending longitudinally, a second member extending longitudinally and hinged to the fixed member, and an anvil member extending longitudinally of the sheet bending brake that is moved into and out of clamping position with the fixed member. A floating compensator comprising a compensator member is pivoted to the bending member and a workpiece engaging pad is pivoted to the compensator member such that as the bending member is swung to bend a workpiece, the pad engages the surface of the workpiece and remains in contact with the workpiece at the same area by the relative pivotal action of the bending member, the compensator member and the pad.

Abstract: A strong, seamless one-piece metal bottle of substantially uniform wall thickness for containing and dispensing gas under pressure is produced from a flat metal piece by a series of deep-drawing operations to provide an elongated cylindrical shell having an open end mouth and a slight flange thereabout. A dimple is formed in its bottom end wall. The flange and an adjacent cylindrical open end mouth portion of the shell is then severed from the main body, and the wall thickness of the new open end mouth portion is tapered from the cylindrical side wall of the shell towards its mouth edge. Thereafter, the tapered open mouth end portion is turned or swaged inwardly into a somewhat blunt, rounded-in nose portion of a substantially uniform thickness that substantially corresponds in the thickness to the side and bottom walls of the formed metal bottle and that has an open end of reduced size suitable for mounting a nipple, ferrule or valve fitting therein.

Abstract: In a railroad spike forging machine of the type comprising a steel stock pointing roller assembly which longitudinally feeds pointed spike blanks along a centerline to a head forming station, a main die of hardened tool steel having a die zone defined between its leading edge and an intermediate point of said first longitudinal dimension, and a wipe zone defined between said intermediate point and the trailing edge of the die by a transversely extending entrance wall surface to the die zone, whereby a transverse wiping of the channel is enabled in said wipe zone. Further, a sensing means generates position signals from the rotation of a pointer roller, and a spike positioning mechanism comprises a first hydraulic cylinder operable transversely to extend a stop mechanism in response to a first position signal, thereby to stop forward motion of a spike blank at an appropriate distance downstream of the die leading edge.

Abstract: An internal mandrel (10) is disclosed which is used for supporting the inner wall (30) of a pipe (12) during bending. The internal mandrel includes a urethane plug (31) which is compressed between the piston (60) of a hydraulic cylinder (56) and an end plate (36). This expands the urethane radially outward into contact with the inner wall (30) of the pipe to support the pipe during bending. Resilient steel strips (88) can be mounted on the exterior surface of the urethane plug (31) at the inside bend of the pipe to increase the effective wall thickness of the pipe at the inner bend to reduce the likelihood of deformation during bending. In a second embodiment, internal mandrel (200) includes an annular urethane plug (204) positioned between a resilient cylinder (202) and the inner wall of the pipe (12).

Abstract: A shaft straightening press including a movable carriage which moves along the length of an "I" beam frame and includes a hydraulic ram used for straightening a shaft placed upon the "I" press bed. The carriage rides upon the lower flange of the "I" beam by means of four wheels fixed to the carriage and making rolling contact with the upper surface of the lower flange. The carriage is locked into place by a pair of hydraulic jacks which lift the carriage, thereby disengaging each of the wheels from rolling contact with the lower flange. The carriage has a cross-sectional shape of a rectangular frame so that when the hydraulic jacks are lifted, the lower end of the rectangular frame of the carriage contacts the lower surface of the lower flange of the "I" beam, thereby securely locking the frame-shaped carriage in place. Slideable precision roller blocks and V-blocks are provided on the upper flange of the "I" beam for positioning and orienting the shaft to be straightened.

Abstract: Pneumatically powered expansion rivet applicator tools. Each of the tools described herein comprise a rigid body adapted to be manually grasped by the user. First and second pneumatic cavities are housed within the body. Pneumatic coupling means associated with the body supply high pressure air to the first cavity. A fitting associated with the body receives the cylindrical shank of an expansion rivet to be installed by the tool. Fluid flow passageway means interconnect the first and second cavities, and an internal valve permits passage of high pressure air through the passageway between the first and second cavities. Piston means are slidably disposed within the second cavity, and, in response to pressurization of the second cavity, virtually instantaneously contacts associated firing pin means to forceably ram the expansion rivet shank, thereby installing the rivet.

Abstract: A test apparatus can test the erosion resistance of a specimen. The apparatus has an enclosure containing in its test chamber an abrasive medium. Also included is a spindle attached to the enclosure. The spindle has an inside end adapted to hold the specimen. A motor coupled to the spindle can spin the inside end at an adjustable angular speed within the medium. Preferably, a thermal jacket can moderate temperature within the spindle apparatus. The apparatus is used to spin the specimen through the abrasive medium at a chosen speed and then measure the extent of erosion.

Abstract: Tracer emission sources which emit tracer gas at a predetermined constant known rate are distributed throughout a building. The preferred source is a small vessel containing a vaporous perfluorocarbon tracer (PFT) substance having a very small bore hole in the top through which the PFT vapor can escape. Time is permitted for the tracer gas to mix uniformly throughout the building and for its concentration to equilibrate with infiltrating air. The concentration of the tracer is then measured and compared to the known volume of air in the building to determine the infiltration rate. In the preferred mode, the concentration is integrated and measured by continuously sampling the tracer gas at a constant rate on activated charcoal adsorbent over a period of several weeks.