delivered the opinion of the Court:

This is an appeal from a decision of the Commissioner' of Patents refusing appellants,- Warren H. Worst and Elmer EKilmer, eight claims for an alleged invention relating to new *342and -useful improvements in window construction. One claim, more specific in its language, was allowed.

Claims 1, 2, and 4 are as follows:

“1. A window sash provided at its corners with a detachable detent, in combination with the window frame having a socket block with which this detent engages.”

“2. A window sash having at its lower corners vertically narrow grooves, in combination with detachable detents having plates adapted to these grooves, and a window frame having socket blocks in which the detents engage.”

“4. The combination of a window sash cord detent consisting of a stock having a recess, and revoluble plates having a stem passing through the stock and into such recess, and provided with a button in such recess, with a socket block having a recess adapted to said button.”

Claims 5, 6, and 8 are for an article of manufacture covering the construction disclosed in the prior claims.

In appellants’ application as amended, they state that their invention “is designed more especially to provide a construction so that the window sash may be turned inwardly, making it unnecessary to remove the storm windows or screens when the outside of sash is to be washed, and also such that the sashes may be readily removed from the frame without having to take anything to pieces or requiring tools.” They then state: “The invention consists primarily in providing the sash at its corners with a detachable detent, and placing in the window frame a socket block with which this detent engages.” Unfortunately, however, their claims are so drawn as to read upon the prior art. Each of the three tribunals of the Patent Office, after a careful examination of the patent to Stumpf, October 13, 1908, and the patent to Zalikowski, May 18, 1889, held those patents an anticipation of the novel features of these claims. We could add nothing to the argument advanced by those tribunals, and therefore affirm the decision of the Commissioner, without prejudice, however, to the right of appellants to apply for leave to amend their claims if so advised.

Affirmed.