The prayer of the bill is for a decree, in the first place, against the Fort Scott, Humboldt & Western Railroad Company, which is a defendant, ordering it to assign to the complainant its claim against the county of Bourbon; and, in the second place, for a decree against Bourbon county and its board of county commissioners, ordering the latter to sign and issue in due form the bonds of said county in the sum of $150,000, payable in 30 years from the date thereof, with semi-annual interest coupons attached, in accordance with the terms of the subscription to the capital stock of the railroad company, and deliver the same to the complainant to be credited at their face value upon his judgment against the railroad company, and for general relief. The relief prayed for does not include a decree against the county of Bourbon for the payment of money, and there is no foundation for such a prayer in the allegations of the bill. It does not charge that the county is indebted in any sum of money presently payable by virtue of its subscription to the capital stock of the railroad company. The legal obligation arising on that subscription is purely statutory, if the subscription itself be valid and binding; and the statutory obligation is satisfied by the issue and delivery to the railroad company of the bonds of the county in payment of the subscription. On the supposition that the subscription creates a legal obligation for its payment in bonds, the refusal of the commissioners of the county to issue and deliver the bonds, however wrongful, is not a breach of the obligation of the county which would give rise to an action against it for the recovery of damages. The breach of obligation in such a case would consist simply in the refusal on the part of the commissioners of the county to perform a ministerial duty, the only remedy for which would be a proceeding at law in the name of the railroad company by a writ of mandamus. That writ, if granted in a direct proceeding therefor by a proper judgment, would be directed against the officers of the county, and would command the performance of the specific duty which the had refused to perform, and would give to the company the precise and specific relief to which to would be entitled. The complainant in the present case has and can have no other or greater rights against the county of Bourbon, or its officers, than are vested in the railroad company. The object of the bill is to subject to the satisfaction of the complainant's judgment against the railroad company the rights of the latter against the county of Bourbon and its officers. The proceeding for that purpose cannot change these rights, nor convert a right to require the delivery of the bonds into a claim for damages for their non-delivery. It is clear that such relief as is alone suitable and adequate to the case cannot be granted in equity. If the proceeding were in the name and on behalf of the railroad company itself, it would, as we have already stated, be at law in mandamus. That the complainant claims to be equitably entitled to be substituted for the railroad company in its rights against Bourbon county may entitle him to a decree against the railroad company for an assignment of its claim, so as to confer upon the complainant the right to use the name of the railroad company in a proceeding against the county and its commissioners; but it does not enlarge the rights of the railroad company against the county and its officers, nor change the remedy so as to enable a court of equity to entertain proceedings in mandamus. The bill might justify a decree against the railroad company for an assignment of its right to the bonds, and requiring the railroad company to permit the use of its name for their recovery by the appropriate proceeding at law. The right to proceed against the county and its commissioners remains still a purely legal right, and can only be prosecuted at law, notwithstanding the equitable nature of the complainant's rights as against the railroad company. As was said in Hayward v. Andrews, 106 U. S. 672, 675, 1 Sup. Ct. Rep. 544: 'If the assignee of the chose in action is unable to assert in a court of law the legal right of the assignor, which in equity is vested in him, then the jurisdiction of a court of chancery may be invoked, because it is the proper forum for the enforcement of equitable interests, and because there is no adequate remedy at law; but when, on the other hand, the equitable title is not involved in the litigation, and the remedy is sought merely for the purpose of enforcing the legal right of his assignor, there is no ground for an appeal to equity, because by an action at law in the name of the assignor the disputed right may be perfectly vindicated, and the wrong done by the denial of it fully redressed. To hold otherwise would be to enlarge the jurisdiction of courts of equity to an extent the limits of which could not be recognized, and that in cases where the only matter in controversy would be purely legal rights.' 'To give a court of equity jurisdiction,' as was said by Mr. Justice WOODS, delivering the opinion of the court in Fussell v. Gregy, 114 U. S. 550, 554, 5 Sup. Ct. Rep. 631, 'the nature of the relief asked must be equitable, even when the suit is based on an equitable title.' This rule was applied in Indemnity Co. v. Water Co., 107 U. S. 205, 2 Sup. Ct. Rep. 279, where it was said that it was entitled to special consideration from the courts of the United States. It follows from this view that the distinction in the jurisdiction of the courts of the United States between proceedings at law and in equity would limit the relief of the complainant, under the present bill, to a decree against the railroad company investing the complainant with its rights and the use of its name in a proceeding to enforce by mandamus the issue and delivery of the bonds alleged to be wrongfully withheld.

The necessity for thus limiting the relief becomes more stringent as well as obvious from another consideration. In the case of Rosenbaum v. Bauer, 120 U. S. 450, 7 Sup. Ct. e p. 633, it was decided by this court upon much deliberation that section 716 of the Revised Statutes, giving power to a circuit court to issue all writs not specifically provided for by statute, which may be necessary for the exercise of its jurisdiction, and agreeable to the usages and principles of law, construed in connection with sections 1 and 2 of the act of 1875, operates to prevent the issuing by the circuit court of a writ of mandamus except in aid of a jurisdiction previously acquired by that court. It is perfectly clear, under the decisions of this court, that no application could be entertained in the circuit court for a writ of mandamus directed against the county commissioners of Bourbon county at the suit and in the name of the railroad company itself. The court would be without jurisdiction, and certainly that lack of jurisdiction cannot be supplied by converting the proceeding into a bill in equity, whether the proceeding be in the name of the railroad company for its own use, or in the name of the railroad company for the use of the complainant, its assignee, or in the name of the assignee himself. The objection is one of substance, and not merely of form. It cannot be waived, and it cannot be ignored.

It follows from this view that, so far as the bill sought the relief prayed for against Bourbon county and its commissioners, the circuit court was without jurisdiction. In point of fact, however, it assumed, jurisdiction, and decided the case on its merits. This, in our opinion, it had no authority to do. For that reason and to that extent the decree of the circuit court dismissing the bill generally must be modified so as to dismiss the bill as against the county of Bourbon and the county commissioners of that county, without prejudice to the right of the complainant, on obtaining a proper assignment and authority from the railroad company to proceed at law in its name, to obtain the issue and delivery of the bonds described in the bill of complaint; and retaining the bill, if the complainant elects and shows himself entitled, as to the Fort Scott, Humboldt & Western Railroad Company, for relief against it alone, for an assignment of its right to the issue and delivery of the bonds of the county, and to the use of its name in a proceeding against the county and its commissioners for the enforcement of such right. It is accordingly so ordered.