The Clasp Locker: Closing a Whole Row of Clasps in One Pull

The clasps "are made with interlocking parts, which when in position, can only engage with each other when at an angle to the line of strain." Their lips "prevent the engagement or disengagement of the hook-portions of the clasps, except when thrown upward, so that the parts stand at an angle to each other of about ninety degrees." By hand, "this is a tedious operation". The guide D has a flat base with upturned lips, a concave or bell-shaped top plate, and a centre piece of angular section that splits the front into two channels which "converge over an angular center ridge or instep" into one at the back. "By moving the guide, so that the separate parts of the clasp enter the respective channels or cam-ways at the front of the guide the entire series of clasps will be delivered from the other or rear end of the guide properly engaged together." Run the other way, it delivers them disengaged. A bail E carries a ring F as a finger pull that can be shifted to either end. Judson notes the guide also "serves to draw the flaps together, and the parts of the shoe tightly about the foot", and that the invention applies wherever clasps of interlocking parts are used — "mail-bags, belts, and the closing of seams uniting flexible bodies".

Cut sixteen small clasp halves from thin brass sheet: eight with a hook turned up at one end, eight with a matching slot and a lip that stops the hook engaging while the halves lie flat. File the edges smooth. Sew them at 6 mm spacing along two edges of denim, hooks on one side and slots on the other, so the halves meet across the gap. Print a guide: two funnel-shaped channels at the front, a ridge between them that lifts the inner ends of both halves, and a single channel at the rear. Pull it along the row and watch each pair tip up, catch and lie down. Change the ridge height to see when it jams and when it fails to tip the clasps far enough.

**Whitcomb L. Judson** of Chicago filed on 7 November 1891; the application was renewed on 18 February 1893 and US 504,038 is dated 29 August 1893. His claims cover the guide block with two ways converging into one, and its shifting finger pull. **Honest limits.** The ramp model treats each clasp as needing a fixed sideways push and ignores the cloth's stiffness; the numbers are examples. Judson's clasps are not the interlocking teeth of the later zip.