The Self-Soaping Shaving Brush: A Soap Stick Inside the Bristles

"The object of my invention is to combine with a shaving-brush a soap-stick and longitudinally-adjustable soap-holder arranged centrally within the brush and its handle, so as to produce a lather on the face simply by dipping the brush in water and brushing it against the face without the need of rubbing the brush on a cake of soap, as is generally done, thus providing a quick, simple, and ready means for lathering the face preparatory to shaving the beard." The bristles are "arranged in the form of an annular ring" round the tube. A knob through a slot in the handle moves the soap down for use; "When not desired for use, the soap-holder and soap-stick are moved upward sufficiently to cause the soap to be protected and covered by the lower part of the handle-tube."

Weigh the soap bar on the kitchen scale and write the weight down. Build a lather in a bowl as in the program, then let the soap dry for a day and weigh it again. The difference is the soap one lather used. Scoop the lather into a measuring jug and read its volume. Repeat with more water, then with less. Note which lather held its peak longest. Put your own soap-per-lather figure into the notebook in place of the examples to see how long a stick the size of Lefavour's would last.

**Woodbury P. Lefavour** of Beverly, Massachusetts, filed US 422,085 on 14 March 1889; it is dated 25 February 1890. **Honest limits.** The capillary formula treats the gaps between bristles as uniform channels with fully wetted walls; real knots are irregular. Stick size, soap density and soap per shave are examples. The weight of soap your lather used is the measurement.