TTÔ FEDERAL REPORTER. �and that evidence -would defeafc the pafent, without further proof of still prior invention by Eagleton. Kellehcr v. Dar- ling, 14 Off. Gaz. 673. And the application, when produced, in order to be effective evidence to carry the date of the invention back to its own date, must be an application for substantially the same invention for which the patent is granted, without material variation or addition. Railway Co. V. Sayles, 97 U. S. 554. The date of the application alone would not be sufScient for that purpose. In this view the original application of Eagleton is important. After the preliminary statement that he haa made an invention, and ref erring to the following as a description, and to the drawing, stating that it "represents a furniture spring, provided, accordiag to my im. provement, vrith a japan covering," he proceeded: "The nature of this invention relates to improvements in helical furniture springs, such as are used for mattresses, sofas, etc., the object of which is to provide steel springs which will not be so liable to injury from corrosion as those now in use. It consists in providing steel springs, such as are com- monly used, with a japan outer covering, Steel springs, as is well known, possess in a much higher degree the requisite qualities of strength, flexibility and elasticity than iron, cop- per or brass, and by reason of the susceptibility of steel to be tempered and thereby regulated to any degree of elasticity, it is much more preferable to use ; but, owing to its great lia- bility to deterioration from corrosion, it is but little used for such springs. �"To obviate this difficulty I propose to provide steel springs coated with japan, which I find to be of great advantage in resisting the corrosive action of the atmosphere on the steel, and whereby steel springs are made very much more durable than any other. To some extent the same purpose may be aceomplished hy coating the spring with tin or zinc, or other similar metal which will not suiïer by corrosion, but the pro- cess of coating with such metal requires the use of acids for cleaning and preparing the steel, which, adhering to the steel, and being to some extent enclosed within the said coating and maintained in contact with the steel, have an injurions ����
