The Hidden Dome gas field, situated in Washakie County, Wyoming, wasdiscovered Sept. 26, 1917. Subsequently five additional gas wells werecompleted and a large reserve was developed. For a number of years this fieldcompletely supplied the domestic market at Basin and Greybull, as well as therefinery at the latter town, and it is still supplying gas in small amounts tothis market. Production is obtained from the sands of the Frontier formation at depthsranging from 1000 to 1500 ft. The original rock pressure was 725 lb. andinitial production ranged from 4,000,000 to 28,000,000 cu. ft. per day perwell. Porosity of the sand, determined from the size of the productive area andthe amount of gas recovered, is over 18 per cent. Area and Management It is estimated that the productive area is about 640 acres. Its outline isindicated on Fig. 5, on which are also shown the locations of holes drilled onthe structure and the area of unit operation. The unit area is owned by the Ohio Oil Co. and development and operation havebeen by this company. No productive well has been completed outside this area-.The entire area was Government land filed on under the placer mining law. Results of Unit Operation With six producing wells, or an average of one to each 160 acres, the pool iscompletely developed. Location of the wells was made with respect to structuralconditions plus the requirement that at least one well be drilled on each160-acre placer claim. Perhaps a somewhat more uniform spacing of the wellsmight have been accomplished and one well eliminated, but it must be borne inmind that the holes, on account of their shallow depth, were not expensive andthat the object was to develop as reliable a reserve as possible. There is nocause to suspect that these holes' have not adequately drained the reservoirand there is every reason to think that any additional wells, which might havebeen drilled under diversified ownership and operation, would have been aneconomic waste.