To all whom it may concern:

Be it known that I, WILLIAM DUNN, of the city of Hamilton, county of Wentworth, Province of Ontario, Canada, have invented new and useful Improvemnts in Seal-Locks,² of which the following is a specification:

My invention relates to that class of locks with which cards or seals are used, for the purpose of showing whether the lock has been opened or not; and it consists first, in the combination, with a lock provided with the usual hasp, of a sliding bar, working longitudinally through the center of the lock and being provided with a parallel groove or recess into which the point of the hasp fits and is thereby fastened, when the hasp and bar are respectively closed.

My invention consists, secondly, in combination, with the before-mentioned bar, of hooked springs, firmly attached to the said bar, for the purpose of pulling out the card or seal when the bar is drawn out to release the hasp.

My invention also consists in the combination, with the lock and bar, of the method of inserting the card or seal in the following manner: When the bar is drawn out, the opening with which it is provided comes directly opposite the aperture constructed for the purpose in the side of the lock, thus allowing the card or seal to be placed against the inside of the glass fixed in the opposite side of the lock. The bar, in closing passes over the back of the card or seal, and closes up the aperture in the side of the lock and prevents the card or seal from being tampered with or taken out, excepting over the index, hereinafter to be mentioned.

My invention furhter consists, in combination with the lock and bar, of a toothed roller, so placed in the interior of the lock that the card or seal, in being drawn out, passes over the teeth of the roller and thus becomes visibly marked, indicating that the lock had been opened.

My invention, lastly, consists in the manner of locking the bar by means of a series of catches, constructed with inclined faces, so as to offer no obstruction in closing the bar, but requiring the aid of a key of peculiar shape before it can be opened.

In the accompanying drawings, Figure 1³ is a side elevation of a lock constructed according to my invention, showing the lock closed and that side in which the glass is fixed. Fig. 2 is an elevation of the opposite side of the lock; also representing the lock as being open. Fig. 3 is a longitudinal transverse section of the lock. Fig. 4 is a vertical sectional view of the lock, showing the interior of the front edge; also a portion of the hasp, the point of which, fitted into the recess of the bar, can also be seen. Fig. 5 is a perspective view of the one side of the bar, with the cap taken away. Fig. 6 is a side view of the key.

¹ In 1881, John Harvey and Isaac McQuesten became partners in the Hespeler Manufacturing Co., which processed raw wool and cotton, a venture that failed miserably and left Isaac bankrupt, (see W2652). Isaac had also had business with William Dunn at this time as well, but it is not clear how the three men all became acquainted with one another.

² For more on Dunn and his patents see W2554a.

³ Figures 1-6 have been omitted, as has the information from the cover letter for the patent.