Rensselaer Republican, Volume 19, Number 49, Rensselaer, Jasper County, 11 August 1887 — Something About Thermometers. [ARTICLE]

Something About Thermometers.

Said a dealer in thermometers to a reporter: “Thermometers are very curious instruments. Sometimes we find one that is all right at ceitein points and at others it will be several degrees out of the way. These variations are caused by irregularities inthe tube. The tubes are very frequently imperfect. When the tube is too large, of course, the registration is several deg eesdower than fit should be. Sometimes the tube is too small and then the mercury shoots up higher than it ought to. The tubes have to be seasoned. This takes several months. When glass is new it changes, expands, contracts and warps almost as badly as greenwood. Very often, after buying a cheap thermometer, the customer has brought it back and said it registered 100° in the shade, when the temperature was' only 90°. The best thermometers are made in London. These imported thermometers are, however, very expensive. Some very good ones are made in this country, at New Lebanon, N. Y , and at Rochester. “How are they made?” was asked.

“The tube is blown to the size wanted, the top being left open. The tube is then hqated to expel the air, and while heated the open end is inserted into some mercury. As the tube cools the mercury runs into the vacuum. The open end is then sealed and the tube placed on a scale. Then it is placed in water of an unknown temperature and the point to which the mercury raises is marked. Several tests like this are made before the instrument is offered for sale.”

“How are .thermometers proved to.be accurate?” ... “There is a place at Harvard College for testing them. They are carefully examined at different temperatures, and any variation is marked. A certificate is given with every instrument that is examined.” “Which scale do you think is the best?” ■ “The centigrade is the one I think should be generally adopted. For the he use of brewers there is a tber*

mometer about three feet long, with a bulb about two feet in length. The scale of-this is short and is only marked for a few degrees above freezing point. Anothert>dd instrument is of English make and can be read in the aark. The tube is filled with a green composition and contains phosphorus. Spirit thermometers are used for very cold' climates, as mercury congeals at 30 degrees below zero. These can not be used to measure extreme heat, as above a certain temperature the liquid expands too fast; it boils at 160 degrees. For very high temperatures the pyrometer takes the place of the thermometer. The heat is measured bv the expansion of metals, and will accurately register up to 700 degrees. Feberile thermometers, for the use of physicians, are very car dully made, and a certificate is sold with them indicating their variations from perfect accuracy. °_ Not Acquainted. In London—Lord Noodle (to Mr. Blaine)—l saw your distinguished countryman yesterday. Blaine—Whom do you mean? “Why, Buffalo Bill. You know him of course.” “No, I have never seen him.” Nord Noodle (aside to a friend)—This man Blaine is an imposter. He is upt acquainted with his own country.—Arkansaw Traveler.