Thermometer
Description
This section is from the book "A Dictionary Of Modern Gardening", by George William Johnson, David Landreth. Also available from Amazon: The Winter Harvest Handbook: Year Round Vegetable Production Using Deep Organic Techniques and Unheated Greenhouses.
Thermometer
This instrument is the only unfailing guide for the gardener in regulating the heat to which he allows the roots and foliage of his plants to be subjected. Fahrenheit's is that employed in England; but as on the Continent others, differently graduated, are employed, and referred to by foreign writers, the following table, showing the synonymous degrees of each, will be useful. [See table].
Fahrenheit's is used chiefly in Britain, Holland, and North America, the freezing point of water on which is at 32°; and its boiling point, 212°. Reaumur's thermometer was that chiefly used in France before the Revolution, and is that now generally used in Spain, and in some other Continental States. In its scale, the freezing point is 0°; and the boiling point, 80°. Celsius or the Centigrade thermometer, now used throughout France, and in the northern kingdoms of Europe, the freezing point is 0°; and the boiling point, 100°. Hence, to reduce degrees of temperature of the Centigrade thermometer and of that of Reaumur to degrees of Fahrenheit's scale, and conversely: -
Fah. | Reau. | Cent. |
212 | 80.0 | 100.0 |
211 | 79.5 | 99.4 |
210 | 79.1 | 98.8 |
209 | 78.6 | 98.3 |
208 | 78.2 | 97.7 |
207 | 77.7 | 97 2 |
206 | 77.3 | 96.6 |
205 | 76.8 | 96.1 |
204 | 76.4 | 95.5 |
203 | 76.0 | 95.0 |
202 | 75.5 | 94.4 |
201 | 75.1 | 93.8 |
200 | 74.6 | 93 3 |
199 | 74.2 | 92.7 |
198 | 73.7 | 92.2 |
197 | 73.3 | 91.6 |
196 | 72.8 | 91.1 |
195 | 72.4 | 90.5 |
194 | 72.0 | 90.0 |
193 | 71.5 | 89.4 |
192 | 71.1 | 88.8 |
191 | 70.6 | 88.3 |
190 | 70.2 | 87.7 |
189 | 69.7 | 87.2 |
188 | 69.3 | 86 6 |
187 | 68.8 | 86.1 |
186 | 68.4 | 85.5 |
185 | 68.0 | 85.0 |
184 | 67.5 | 84.4 |
183 | 67.1 | 83.8 |
182 | 66.6 | 83.3 |
181 | 66.2 | 82.7 |
180 | 65.7 | 82.2 |
170 | 65.3 | 81.6 |
178 | 64.8 | 81.8 |
177 | 644 | 80.5 |
176 | 64.0 | 80.0 |
17.5 | 63.5 | 79.4 |
174 | 63.1 | 78.8 |
173 | 62.6 | 78.3 |
172 | 62.2 | 77.7 |
171 | 61.7 | 77.2 |
170 | 61.3 | 76.6 |
169 | 60.8 | 76.1 |
168 | 60.4 | 75.5 |
107 | 60.0 | 75.0 |
166 | 59 5 | 74.4 |
165 | 59.1 | 73.8 |
164 | 59.6 | 73.3 |
163 | 58.2 | 72.7 |
169 | 57.7 | 72.2 |
161 | 57.3 | 71.6 |
160 | 56.8 | 71.1 |
159 | 56.4 | 70.5 |
158 | 56.0 | 70.0 |
157 | 55.5 | 69.4 |
156 | 55.1 | 68.8 |
155 | 54.6 | 68.3 |
151 | 54.2 | 67.7 |
Fah. | Reau. | Cent. |
153 | 53.7 | 67.2 |
152 | 53.3 | 06.0 |
151 | 52.8 | 00.1 |
150 | 53.4 | 65 5 |
149 | 52.0 | 65.0 |
148 | 51.5 | 65.4 |
147 | 51.1 | 63.8 |
146 | 50.6 | 63.3 |
145 | 50.2 | 62 7 |
144 | 49.7 | 62 2 |
143 | 49.3 | 61.6 |
142 | 48.8 | 61.1 |
141 | 48.4 | 60 5 |
140 | 48.0 | 60.0 |
139 | 47.5 | 59.4 |
138 | 47.1 | 58.8 |
137 | 46.6 | 58.3 |
136 | 46.2 | 57.7 |
135 | 45.7 | 57.2 |
134 | 45.3 | 50.0 |
133 | 44.8 | 56.1 |
132 | 44.4 | 55.5 |
131 | 44.0 | 55.0 |
130 | 43.5 | 54.4 |
129 | 43.1 | 53.8 |
128 | 42 6 | 53.3 |
127 | 42.2 | 52.7 |
126 | 41.7 | 52.2 |
125 | 41.3 | 51.6 |
124 | 40.3 | 51.1 |
123 | 40.4 | 50.5 |
122 | 40.0 | 50.0 |
121 | 39.5 | 49.4 |
130 | 39.1 | 48.8 |
119 | 38.6 | 48.3 |
118 | 38.2 | 47.7 |
117 | 37.7 | 47.2 |
116 | 37.3 | 40 6 |
115 | 36.8 | 46.1 |
114 | 36.4 | 45.5 |
113 | 36.0 | 45.0 |
112 | 35.5 | 44.4 |
111 | 35.1 | 43.8 |
110 | 34.6 | 43.3 |
109 | 34.2 | 42.7 |
108 | 33.7 | 42.2 |
107 | 33.3 | 41.6 |
106 | 32.8 | 41.1 |
105 | 32.4 | 40.5 |
104 | 32.0 | 40.0 |
103 | 31.5 | 39.4 |
102 | 31.1 | 38.8 |
101 | 30.6 | 38.3 |
100 | 30.2 | 37.7 |
99 | 29.7 | 37.2 |
98 | 29.3 | 36.6 |
97 | 28.8 | 36.1 |
96 | 28,4 | 35.5 |
95 | 29.0 | 35.0 |
Fall. | Reau. | Cent. |
94 | 27.5 | 34.4 |
93 | 27.1 | 33.8 |
92 | 20.6 | 33.3 |
91 | 26.2 | 32.7 |
90 | 25.7 | 32.2 |
89 | 25.3 | 31.6 |
88 | 24.8 | 31.1 |
87 | 21.4 | 30.5 |
86 | 24.0 | 30.0 |
85 | 23 5 | 29 4 |
84 | 23.1 | 28.8 |
83 | 22.6 | 28.3 |
82 | 22.2 | 27.7 |
81 | 21.7 | 27 2 |
80 | 21.3 | 26.6 |
79 | 20.8 | 20.1 |
73 | 20.4 | 25.5 |
77 | 20.0 | 25.0 |
76 | 19 5 | 24 4 |
75 | 19.1 | 23.8 |
74 | 18.6 | 23.3 |
7:! | 18.2 | 22.7 |
72 | 17.7 | 22.2 |
71 | 17.3 | 21.6 |
70 | 16.8 | 21.1 |
69 | 16.4 | 20.5 |
68 | 16.0 | 20.0 |
67 | 15.5 | 19.4 |
66 | 15.1 | 18.8 |
65 | 14.6 | 18.3 |
64 | 14 2 | 17.7 |
63 | 13.7 | 17.2 |
62 | 13.3 | 16 6 |
61 | 12.8 | 16.1 |
60 | 12.4 | 15.5 |
59 | 12.0 | 15.0 |
58 | 11.5 | 14.4 |
57 | 11.1 | 13.8 |
56 | 10.6 | 13.3 |
55 | 10.2 | 12.7 |
54 | 9.7 | 12.2 |
53 | 9.3 | 11.6 |
52 | 8.8 | 11.1 |
51 | 8.4 | 10.5 |
50 | 8.0 | 10.0 |
49 | 7.5 | 9.4 |
48 | 7.1 | 8.8 |
47 | 6.6 | 8.3 |
46 | 6.2 | 7.7 |
45 | 5.7 | 7.2 |
44 | 5.3 | 6.6 |
43 | 4.8 | 6.1 |
42 | 4.4 | 5.5 |
41 | 4.0 | 5.0 |
40 | 3.5 | 44 |
39 | 3.1 | 3.8 |
38 | 2.0 | 3.3 |
37 | 2.2 | 2.7 |
36 | 1.7 | 2.2 |
Fah. | Reau. | Cent. |
35 | 1.3 | 1.6½ |
34 | 0.8 | 1.1 |
33 | 0.4 | 0.5 |
32 | 0.0 | 0.0 |
31 | - 0.4 | - 0.5 |
30 | - 0.8 | - 1.1 |
29 | - 1.3 | - 1.6 |
28 | - 1.7 | - 2.2 |
27 | - 2.2 | - 2.7 |
26 | - 2.6 | - 3.3 |
25 | - 3.0 | - 3.8 |
24 | - 3.5 | - 4.4 |
23 | - 4.0 | - 5.0 |
22 | - 4.4 | - 5.5 |
21 | - 4.8 | - 6.1 |
20 | - 5.3 | - 6.6 |
19 | -5.7 | - 7.2 |
18 | - 6.2 | - 7.7 |
17 | - 6.6 | - 8.3 |
16 | - 7.1 | - 8.8 |
15 | - 7.5 | - 9.5 |
14 | - 8.0 | -10.0 |
13 | - 8.4 | -10.5 |
12 | - 8.8 | -11.1 |
11 | - 9.3 | -11.6 |
10 | - 9.7 | -12.2 |
9 | -10.2 | -12.7 |
8 | -10.6 | -13.3 |
7 | -11.1 | -13.8 |
6 | -11.5 | -14.4 |
5 | -12.0 | -15.0 |
4 | -12.4 | -15.5 |
3 | -12 8 | -16.1 |
2 | -13.3 | -16.6 |
1 | -13.7 | -17.2 |
0 | -14.2 | -17.7 |
- 1 | -14.6 | -18.3 |
- 2 | -15.1 | -18.8 |
- 3 | -15.5 | -19.4 |
- 4 | -16.0 | -20.0 |
- 5 | -16.4 | -20.5 |
- 6 | -16.8 | -21.1 |
- 7 | -17.3 | -21.6 |
- 8 | -17.7 | -22.2 |
- 9 | -18.2 | -22.7 |
-10 | -18.6 | -23.3 |
-11 | -19.1 | -23.8 |
-12 | -19.5 | -24.4 |
-13 | -20.0 | -25.0 |
-14 | -20.4 | -25.5 |
- 15 | -20.8 | -26.1 |
-16 | -21.3 | -26.6 |
-17 | -21 7 | -27.2 |
- 18 | -22.2 | -27.7 |
-19 | -22.6 | -28.3 |
-20 | -23.1 | -28.8 |
Rule 1. Multiply the Centigrade degrees by 9, and divide the product by 5; or multiply the degrees of Reaumur by 9, and divide by 4; then add 32 to the quotient in either case, and the sum is the degrees of temperature of Fahrenheit's scale.
Rule 2. From the number of degrees on Fahrenheit's scale, subtract 32; multiply the remainder by 5, for Centigrade degrees, or by 4 for those of Reaumur's scale, and the product, in either case, being divided by 9, will give the temperature required.
To ascertain the internal temperature of a hot-house, the thermometer should be fixed near its centre, against a pillar, and under a cupola, or little roof, shading it from the sun.
A self-registering thermometer should be in every house, for it shows the highest and lowest degrees of heat which have occurred in the twenty-four hours; and, therefore, serves as a check upon those to whose care they are entrusted.
Bregazzi's bark-bed thermometer is an excellent instrument for ascertaining the bottom heat of hotbeds, bark-pits, etc. It is a thermometer inclosed in a metal tube, perforated to admit the heat, pointed so as to be easily thrust down and with a small door in the side, for observing the degree of temperature shown by the scale. Fig. 166.
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