Generally speaking, the price of the meter is a subordinate consideration.
The gas current is simultaneously observed by a suitable meter, which, with subsidiary corrections for pressure, temperature, &c., gives the necessary data for deducing calorific value.
The ultimate goal, I submit, is not to optimize just meter by meter but what I call "grape by grape," down to each individual piece of flora and fauna.
Later apparatus, such as Pettersson's bifilar current-meter or his more recent electric-photographic apparatus, and Nansen and Ekman's propeller current-meter, measure both the direction and the velocity at any moderate depth from an anchored vessel.
A modification of the above meter with some mechanical improvements has been devised by S.