The Heated Curling Iron: Putting the Fire in the Handle

"The invention relates to a novel means for heating the well-known curling iron or tongs used by hair-dressers for curling hair, and it consists in combining with and so as to form part of such instrument a burner or tube through which gas or other inflammable fluid is burned while the instrument is being used, whereby the curling-iron may be kept constantly and uniformly heated; also, in combining with such an instrument, made with a gas or other burner, a steam-generating chamber, arranged in such manner that the curling-tube may be heated by the circulation of steam." The fuel chamber in the handle "may be a reservoir for containing alcohol or other fluid", or a chamber for gas with an extension "for attachment of a flexible gas tube to be applied to a common gas-burner". With it, "the trouble and annoyance attending the heating of an iron in a stove or lamp and the cooling of the same while being used are avoided, no attention being required after once lighting the flame at the burner".

Do not build a gas-fired iron: use an electric curling iron, which holds its temperature with a thermostat as Maxim's burner tried to. Heat the iron and measure the barrel with a thermocouple pressed against it at each setting. An infrared thermometer reads a shiny barrel too low. Write the settings and temperatures down. Take three sections of the same size. Curl them at one setting, held for 5, 10 and 15 seconds, and let each cool before touching it. Measure the length of each curl with a ruler straight away and again after an hour. The curl that shortens least held best; use the lowest setting and time that gives it.

**Hiram S. Maxim** of Boston received US 57,354, dated 21 August 1866. The drawing shows the burner and flame chamber in the shank, with the steam chamber above them. **Honest limits.** The rod, loss coefficient, lock mass and heat share in the notebook are examples; the model treats each lock as taking a fixed share of the temperature gap. The 100 °C ceiling holds only for steam at atmospheric pressure, and the patent does not say whether the steam space is open or closed. Your thermocouple readings and curl lengths are the measurement.