Recording instrument to measure microbal gas production

Claim 1

A measuring instrument to provide a continuous record of the gas production of at least one microbal sample as a function of time, comprising, in combination: at least one sample container defining an enclosed chamber with means of ingress and egress thereto carrying a microbal sample and communicating for gas transmission with a fluid reservoir providing an enclosed chamber filled with fluid and communicating in its lowermost portion for fluid transmission with a vertical measuring cylinder having a vertical height and defining a contained volume greater than the vertical height and contained volume of said fluid reservoir and positioned with its uppermost part vertically above the uppermost part of the fluid reservoir; a float carried for vertical motion in response to fluid variations within the measuring cylinder and mechanically communicating with a marker structure having a marking device movable responsive to the motion of the float by a mechanical linkage therebetween; and a recorder having a elongate tape movable perpendicularly to the motion of the marker and positioned in operative contact therewith to be marked upon by the marker to make a tracing upon the tape indicating the vertical position of the marker relative thereto.