Monday, April 12, 2010

What is a "Sixe's Thermometer"?

Lovecraft mentions he used a standard thermometer, and a Sixe's thermometer. In the U.S. it has been abbreviated, sometimes, to Six's thermometer. HPL used the expanded spelling.

Above is a modern item, and shows: A Maximum Minimum thermometer. The scales are Fahrenheit on the inside of the U and Celsius on the outside. The current temperature is 23 degrees Celsius, The maximum recorded is 25, and the minimum is 15, both read from the base of the small markers in each arm of the U tube. The bulbs are hidden by a plastic housing.

These were not easy to maintain, and may have easily caused Lovecraft to be late for school. He may have sometimes had a mercury mess. *

The Sixe's thermometer is notoriously known for separations in the mercury column, in particular after shipment, though accidental knocks have been known causes as well. Separations can usually be corrected by swinging the thermometer like a large old school fever thermometer. The centrifugal force will then force the mercury together again. Should the markers be partly buried in the mercury they can either be pulled up again with the magnet or put to a temperature change that leaves the markers uncovered. It is however important NOT to use a magnet to pull up markers in the push button type because there's a risk of damaging the weak magnet behind the scale or magnetize the steel in the markers with equal fatal consequences - either weakening or enhancing the pulling force against the capillary tube on all or part of the scale.

How it works: ... consists of a U-shaped capillary tube with two separate temperature readings, one for the maximum temperature and one for the minimum temperature. There are bulbs at the top of each arm of the U-shaped tube. The one at the top of the minimum reading scale contains alcohol, the other contains a vacuum or low pressure alcohol vapour.

In the bend of the U is a section of mercury element mercury which is pushed around the tube by the expansion and contraction of the alcohol in the first bulb. It is the alcohol which measures the temperature, the mercury indicates the temperature reading on both scales.

At any given time the reading of the mercury should be the same on both the maximum and minimum scales. If not then the instrument scales are not correctly positioned.

As the mercury moves it pushes 2 small steel markers which are sprung into the tube. They record the furthest point reached by the mercury in each arm of the tube. When the temperature reverses and the mercury is moved in the opposite direction by the expansion or contraction of the alcohol, the sprung markers remain in the tube at the furthest position they have been pushed by the mercury. They thus record the extremes of temperature experienced by the device since it was last reset.

Chrispy was unable to find a 1906 style thermometer, but here is one from 1869.

We should also discuss the other kind of thermometer. Today, we take temperatures by shining a little light and reading an LED (light emitting diode). Not so in the days of slide rules. A glass tube, sealed on both ends, was filled with mercury and scored with degree marks. As it got warmer, the mercury expanded, and as it cooled it got smaller. These were relatively fragile, and if you handled them with cold, or wet fingers, you got a *whoops* with a resulting shatter of glass and a hundred tiny droplets of silver mercury that rolled as if possessed. One cleanup was to sprinkle silver dust which immediately absorbed the droplets and amalgamated the particles and made clean up easy. Beware if you had a 14K gold ring, for it would forever silverize the gold. If you had a keen eye, you could easily read 1/100-th of a degree in a very accurate (precise) thermometer.

*Mercury. Chrispy, from an early age was fascinated with science. He accompanied his mother as she cleaned offices, and back in the 60's (I'm sure the statute of limitations has expired, and all adults are now deceased) he would sneak to the dentist's bench and play with the little beads of mercury. Oh how they rolled, and dust beaded up on theri surface, and if you pushed them together, they merged ! The metal did appear alive to that little boy.

In the 1980's, in a lab I worked in, the employees often broke the mercury thermometers. (Did they ever!) When I became lab manager, and tired of chasing little droplets of mercury (since I was the designated person to chase the droplets and who actually had a chemistry degree), I switched everyone to the then-new inexpensive digital thermometers (which they also destroyed on occassion).

In Lovecraft's day, mercury was "quicksilver" and commonly used in many purposes, but mostly in dental amalgams and thermometers. If he was like any other scientist of his era, he probably knew the minimal risks and cleaned up lots of mercury spills. Glass is fragile, and accidents happen.

Mercury is a neurotoxin, and the vapors do readily evaporate and can be respirated. Do NOT use mercury. There are so many safer ways to do the job these days.

No, I don't think Lovecraft was in any way harmed if he handled mercury. I think that upon this subject I can be sure, it did not influence his weird tales.

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