After long search, and close inquiry in numerous salt-works, and as the result of his study of salt-making in pans of every size, Chrysel came to the conclusion that a single pan--“26 feet long, 18 feet broad, and 12 inches deep, with two furnaces, in a roomy salt-works with sufficient room for the workmen and baskets on both sides of the pan”--was to be preferred to all others. But this considered judgment was amended after further application to the problem by advocating an increase in length without changing the breadth of the pan. His ultimate verdict was in favour of a pan 52 ft. long, 18 ft. broad, and 1 ft. deep, with a capacity of 936 cubic feet of brine, equipped with two furnaces, and he declared that this pan, producing about 638 cwt. of salt per week, at a cost of £10 5s. 6d. for fuel, and selling for £127 15s. 6d., and giving a profit of £117 10s. was “the perfect article.” Although, as I have pointed out, Chrysel’s patent was principally concerned with the arrangement of the brine pans, which were so arranged as to obtain the maximum amount of heat from the fuel consumed in the furnaces, in the course of his experiments he evolved an improved, if by no means a perfect, furnace. The peculiar nature of the superiority effected was based on the common knowledge that it is the natural tendency of fire heat and smoke to escape into the open air and disappear. He proceeds: “If, however, they are confined and shut up in a furnace under a salt pan they still require an opening to escape to the chimney else the fire cannot burn and is extinguished. If however the opening and place of exit into the draughts and chimney is too large and wide, as it is generally, and particularly under salt pans, not only will the draught of Air cause Wood and Coal to be more rapidly consumed and changed into Ashes which will choke the fire but also the fireheat and smoke will, by the draught of the air, hasten into the draughts and chimney, and the bottom of the pan will hardly be touched and scarcely half the work be done. On the contrary, if the opening and exit into the draughts and chimney has a proper proportion, according to the different sizes of the Pans and to the requisite Fire in the Furnace under the pan, the Fireheat and Smoke will be longer contained under the pan and that, steadily coming from the Furnace, will be increased and strengthened, so that double work under the pan will result, and wood or coal will not so rapidly be burnt to ashes but last longer and consequently do more work. All that is required in this is to calculate the mathematical proportion between the different sizes of the pans, the Furnace and the Fires and between the opening and Exit into the draughts and chimney, and to apply it.”