Dacosta began to dig for ore in the following year. News of his enterprise spread rapidly, and this long neglected mine was heralded in the newspapers as "one of the first discoveries yet made in the United States."[92] On December 15, 1804, Dacosta purchased a one-half undivided interest in "Mill Grove,"[93] giving, as we believe, a mortgage, and hoping to pay for his share out of the profits of the lead mine. Thereafter for about two years he continued to conduct the farm and develop the mine, upon the basis of a one-half interest, in addition to a small salary.[94] In case the mine proved a success, it was understood that young Audubon was to be taken into the business and thus obtain a means of self-support. Dacosta was at first averse to forming a company, but the Quaker tenant, William Thomas, who caught the fever, and who was thought to possess more knowledge of the mine than he was ready to divulge, seems to have been taken conditionally into the partnership. Dacosta made full reports of his progress to the old sailor at Couëron, who came regularly to Nantes to send back to America his well considered answers and candid advice. Dacosta also called persistently for money, but as Lieutenant Audubon was unable to meet these demands, he applied to his friend François Rozier, a wealthy merchant at Nantes, to supply the needed capital. Rozier invested 16,000 francs, and to complicate matters took a mortgage upon one-half of the value of "Mill Grove," in which the earlier proprietor, John Augustin Prevost, as well as Francis Dacosta, was also interested. Jean Audubon, Dacosta and Rozier thus became partners in an enterprise which seems to have swallowed up all of the money which was advanced and never to have made any substantial returns. The eventual failure of the lead mine must be attributed in part to the high cost of materials, as well as to the expense involved in uncovering the ore, a difficulty which all later exploiters seem to have found insuperable. Dacosta also discovered that the management of his youthful charge was quite as difficult as making a success of the mine. His grievances on this score were duly reported at Couëron, and if he was really trying to carry out the instructions which came from France, it was perhaps no wonder that he received the undisguised contempt of his rebellious pupil. How just the naturalist's charges against his hated tutor may have been, will be considered in the sequel, but Lieutenant Audubon's letters,[95] to be given presently at length, clearly show that in spite of the strained relations which later ensued, Dacosta continued to enjoy his confidence for some time after young Audubon's return to France in 1805. The more serious troubles that followed seem to have arisen from entanglements into which all were later drawn.