Newton scale
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The Newton scale is a
Newton used
The linseed thermometer could be used up to the melting point of tin. For higher temperatures, Newton used a "sufficiently thick piece of iron" that was heated until red-hot and then exposed to the wind. On this piece of iron, samples of metals and alloys were placed, which melted and then again solidified on cooling. Newton then determined the "degrees of heat" of these samples based on the solidification times, and tied this scale to the linseed one by measuring the melting point of tin in both systems. This second system of measurement led Newton to derive his law of convective heat transfer, also known as Newton's law of cooling.
In his publication, Newton gives 18 reference points (in addition to a range of meteorological air temperatures), which he labels by two systems, one in arithmetic progression and the other in geometric progression, as follows:
0 | the heat of air in winter at which water begins to freeze. This point may be accurately determined by pressing the thermometer into melting snow. | |
0,1,2 | the heats of air in winter | |
2,3,4 | the heats of air in spring and autumn | |
4,5,6 | the heat of air in summer | |
6 | the heat at midday about the month of July | |
12 | 1 | the greatest heat which a thermometer takes up when in contact with the human body |
14 | 1¼ | the greatest heat of a bath which one can endure for some time when the hand is dipped in and is kept in constant movement |
17 | 1½ | the greatest heat of a bath which one can endure for some time when the hand is dipped in and is kept still |
20 | the heat of a bath in which liquid wax slowly becomes solid and assumes transparency | |
24 | 2 | the heat of a bath in which solid wax melts and is conserved in liquid state without boiling |
28 | 2¼ | intermediate point between the boiling point of water and the melting point of wax |
34 | the heat at which water boils vehemently (the temperature at which water begins to boil is given as an additional value in the description, as 33) | |
40 | melting point of an alloy of one part lead, four parts tin and five parts bismuth | |
48 | 3 | melting point of an alloy of equal parts of bismuth and tin |
57 | 3¼ | melting point of an alloy of one part bismuth and two parts tin |
68 | 3½ | melting point of an alloy of one part bismuth and eight parts tin |
81 | melting point of bismuth | |
96 | 4 | melting point of lead |
114 | 4¼ | heat of bodies that can barely be seen glowing at night |
136 | 4½ | heat of bodies that can be seen glowing by twilight |
161 | heat of bodies that can be seen glowing by daylight | |
192 | 5 | heat of iron glowing as brightly as possible |
See also
- Outline of metrology and measurement
- Comparison of temperature scales
- List of obsolete units of measurement
References
- ^ Published anonymously as "Scala graduum Caloris. Calorum Descriptiones & signa." in Philosophical Transactions, 1701, 824–829; ed. Joannes Nichols, Isaaci Newtoni Opera quae exstant omnia, vol. 4 (1782), 403–407. Mark P. Silverman, A Universe of Atoms, An Atom in the Universe, Springer, 2002, p. 49.
- S2CID 118599488.
External links
- Photo of an antique thermometer backing board c. 1758 – marked in four scales; the first is Newton's.