Reservoir seal

Claim 1

A LIQUID RESERVOIR INCLUDING A SEAL COMPRISING A CONDUIT HAVING A FORWARD END AND A REAR END AND HAVING A BORE OF GREATER-THAN-CAPILLARY CROSS-SECTIONAL AREA WHICH IS SUBJECT TO ATMOSPHERIC PRESSURE, PISTON MEANS SLIDABLE WITHIN THE CONDUIT AND HAVING A PERIPHERAL SHAPE SIMILAR TO BUT SLIGHTLY SMALLER THAN THAT OF THE INSIDE SURFACE OF THE CONDUIT SO AS TO PROVIDE A SPACE OF CAPILLARY DIMENSIONS BETWEEN THE ADJACENT SURFACES OF THE PISTON MEANS AND THE CONDUIT, URGING MEANS EFFECTIVE WHEN THE RESERVOIR CONDUIT IS IN A FIRST POSITION BETWEEN HORIZONTAL ORIENTATION AND AN ORIENTATION WHEREIN ONE OF SAID REAR END AND SAID FORWARD END IS LOWER THAN THE OTHER THEREOF FOR APPLYING A COMPONENT OF FORCE TO THE PISTON MEANS DIRECTED IN THE LONGITUDINAL DIRECTION OF THE CONDUIT IN A MANNER TENDING TO THRUST THE PISTON MEANS OUT OF A LIQUID IN THE CONDUIT WHICH IS SUFFICIENT TO BALANCE ANY CAPILLARY FORCES TENDING TO DRAW THE PISTON MEANS INTO A LIQUID IN THE CONDUIT, THEREBY PREVENTING SEEPAGE OF LIQUID THROUGH THE SPACE BETWEEN THE PISTON MEANS AND THE CONDUIT, AND MEANS FOR MODIFYING THE COMPONENT OF FORCE APPLIED BY THE URGING MEANS TO THE PISTON MEANS WHEN THE RESERVOIR CONDUIT IS IN A SECOND POSITION WHEREIN SAID OTHER OF SAID FORWARD AND REAR ENDS IS LOWER THAN SAID ONE THEREOF, SAID MODIFYING MEANS BEING INEFFECTIVE TO VARY THE COMPONENT OF FORCE APPLIED BY SAID URGING MEANS TO SAID PISTON MEANS IN SAID FIRST POSITION OF SAID CONDUIT.