In the Fahrenheit thermometer, the freezing point of water (actually the temperature of melting ice) is indicated by the number 32, and the boiling point by 312; in the Centigrade instrument, these respective temperatures are indicated by 0 and 100, and in the Reaumur instrument, by 0 and 80. The first-named thermometer owes its system of numeration to G. D. Fahrenheit, a German physicist living in Holland early in the eightjenth century, and elected a Fellow of the Royal Society of London in 1724; the Fahrenheit thermo-meter is used principally in Great Britain and Holland. The Centigrade thermometer, invented in 1712 by Anders Celsius, a (Swede, is the standard instrument for scientific investigations; whilst the Reaumur thermometer, which is the invention of a Frenchman of that name contemporary with Celsius, is used in Germany and Russia, hut is being superseded. On the Continent the Centigrade instrument, which is in popular use there, is known as the Celsius thermometer. To convert F. degrees to C, 5 subtract 32 and multiply by 5/9; for example, 77° F. = ((77 -32)x 5)/9 = 25 C. To convert F. degrees to R., subtract 32 and multiply by 4/9 for example, Tl° F. = ((77-32)x4)/9 = 20 R. To convert C. degrees to F., multiply by 9/5 and add 32; for example, 25° C. = (((25x9)/5)+32) = 77° F. To convert C. degrees to R., multiply by -; for example, 25° C. = (25x4)/5 = 20 R. To convert R. degrees 9 to F., multiply by 9/4 and add 32; for example, 29 R. = (((20x9)/4)+32) = 77° F. To convert R. degrees to C, multiply by 9/4; for example, 20° R. = (20x5)/4 = 25° C. The tables on the previous page provide for the conversion of any degree between the freezing and boiling points of water in any one of the three systems above noted to either of the other systems.

Table For Conversion Of Thermometer Degrees

c.

F.

R.

0

32

0

•5

33

•4

1

33.8

•8

11

34

•88

1.2

34.2

1

16

35

1.3

2

35.6

1.6

22

36

1.7

2.5

36.5

2

2.7

37

2.2

3

37.4

2.4

33

38

2.6

3.7

38.7

3

3.8

39

31

4

39.2

3.2

1.1

10

3.5

5

41

4

5.5

12

1.1

6

42.8

4.8

61

43

4.88

.2

43.2

5

6.6

44

5.3

7

44.6

5.6

72

45

5.7

7.5

45.5

6

7.7

46

6.2

8

46.4

6.4

8.3

47

6.6

87

47.7

7

8.8

48

71

9

48.2

7.2

9.4

49

7.5

10

50

8

10.5

51

8.4

11

51.8

8.8

11.1

52

8.88

11.2

52.2

9

11.6

53

9.3

12

53.6

9.6

12.2

54

9.7

12.5

54.5

10

127

55

10.2

13

55.4

10.4

13.3

56

10.6

13.7

56.7

11

13.8

57

11.1

14

57.2

11.2

14.4

58

11.5

15

59

12

15.5

60

12.4

16

60.8

12.8

161

61

12.88

16.2

61.2

13

16.6

62

13.3

17

62.6

13.6

17.2

63

13.7

17.5

63.5

14

177

64

14.2

18

61.4

14.4

18.3

65

14.6

18.7

65.7

15

18.8

66

151

19

66.2

15.2

19.4

67

15.5

20

68

16

20.5

69

16.4

21

69.8

16.8

211

70

16.88

21.2

70.2

17

21.6

71

17.3

22

71.6

17.6

22.2

72

17.7

22.5

72.5

18

22.7

73

18.2

23

73.4

18.4

23.3

74

18.6

23.7

74.7

19

23.8

75

191

24

75.2

19.2

24.4

76

19.5

25

77

20

C.

F.

R.

25.5

78

20.4

26

78.8

20.8

26.1

79

20.88

26.2

79.2

21

26.6

80

21.3

27

80.6

21.6

27.2

81

21.7

27.5

81.5

22

27.7

82

22.2

28

82.4

22.4

28.3

83

22.6

28.7

83.7

23

28..8

84

23.1

29

84.2

23.2

29.4

85

23.5

30

86

24

30.5

87

24.4

31

87.8

24.8

31.1

88

24.88

31.2

88.2

25

31.6

89

25.3

32

89.6

25.6

32.2

90

25.7

32.5

90.5

26

32.7

91

26.2

33

911

26.4

33.3

92

26.6

33.7

92.7

27

33.8

93

27.1

34

93.2

27.2

34.4

94

27.5

35

95

28

35.5

96

281

36

96.8

28.8

3fi.l

97

28.88

36.2

97.2

29

36.6

98

29.3

37

98.6

29.6

37.2

99

29.7

37.5

99.5

30

37.7

100

30.2

38

100.4

30.4

38.3

101

30.6

38.7

101.7

31

38.8

102

31.1

39

102.2

31.2

39.4

103

31.5

40

104

32

40.5

105

32.4

41

105.8

32.8

411

106

32.88

41.2

106.2

33

41.6

107

33.3

42

107.6

33.6

42.2

108

33.7

42.5

108.5

34

42.7

109

31.2

43

109.4

34.4

43.3

110

34.6

43.7

110.7

35

43.8

111

35.1

44

111.2

35.2

44.4

112

35.5

45

113

36

45.5

114

36.4

46

114.8

36.8

46.1

115

36.88

46.2

115.2

37

46.6

116

37.3

47

116.6

37.6

47.2

117

37.7

47.5

117.5

38

17.7

118

38.2

48

118.4

38.4

48.3

119

38.6

48.7

119.7

39

48.8

120

391

49

120.2

39.2

49.4

121

39.5

50

122

40

C.

F.

R.

50.5

123

40.4

51

123.8

40.8

51.1

124

40.88

51.2

121.2

41

51.6

125

41.3

52

1:5.6

41.6

52.2

126

11-7

52.5

126.5

42

52.7

127

42.2

53

127.4

42.4

53.3

128

42.6

53.7

128.7

43

53.8

129

43.1

54

129.2

43 2

51.4

130

43.5

55

131

44

55.5

132

44.4

56

132.8

44.8

56.1

133

44.88

56.2

133.2

45

56.6

131

45.3

57

134.6

4.5.6

57.2

135

45.7

57.5

135.5

46

57.7

136

46.2

58

136-4

46.4

58.3

137

46.6

58.7

137.7

47

58.8

138

47.1

59

138.2

47.2

59.4

139

47.5

69

140

48

60.5

141

48.4

61

141.8

48.8

61.1

142

48.88

61.2

142.2

49

61.6

143

49.3

62

143.6

49.6

62.2

144

49.7

62.5

144.5

50

62.7

145

50.2

63

145.4

50.4

63.3

116

50.6

63.7

146.7

51

63.8

147

511

64

147.2

51.2

64.4

148

51..5

65

119

52

65.5

150

52.4

66

150.8

52.8

66.1

151

52.88

66.2

151.2

53

66.6

152

53.3

67

152.6

53.6

67.2

153

53.7

67.5

153.5

54

67.7

151

54.2

68

154.4

54.4

68.3

155

54.6

68.7

155.7

55

68.8

156

55.1

69

156.2

55.2

69.4

157

55."5

70

158

56

70.5

159

56.4

71

159.8

56.8

71.1

160

56.88

71.2

160.2

57

71.6

161

57.3

72

161.6

57.6

72.2

162

57.7

2.5

162.5

58

72.7

163

58.2

73

163.4

58.4

73.3

164

58.6

73.7

161.7

59

73.8

165

59.1

74

165.2

59.2

71.1

166

59.5

75

107

60

c.

P.

R.

75.5

108

60.4

76

168.8

60.8

76.1

169

60.83

70.2

169.2

61

70.0

170

61.3

77

170.6

61.6

77.2

171

61.7

77.5

171.5

62

777

172

62.2

7S

172.4

62.4

78.3

173

62.6

787

173.7

63

78.8

174

63.1

79

174.2

63.2

79.1

175

63.5

80

176

64

80.5

177

64.4

81

177.8

64.8

81.1

178

64.88

81.2

178.2

65

81.6

179

65.3

82

179.6

65.6

82.2

180

65.7

82.5

180.5

66

82.7

181

66.2

83

181.4

66.4

83.3

182

66.6

83.7

182.7

67

83.8

183

67.1

84

183.2

67.2

84.4

184

67.5

85

185

68

85.5

186

68.4

8(5

186.8

68.8

86.1

187

68.88

85.2

187.2

69

86.6

183

69 3

87

188.6

69.6

87.2

189

69.7

87.5

189.-5

70

87.7

190

70.2

88

190.4

70.4

88.3

191

70.6

88.7

191.7

71

88.8

192

71.1

89

192.2

71-2

89.4

193

71.5

90

194

72

90.5

195

72.4

91

195.8

72.8

911

196

72.88

91.2

196.2

73

91.6

197

73.3

92

197.6

73.6

92.2

198

73.7

92.5

198.5

74

92.7

199

74.2

93

199.4

74.4

93.3

200

74.6

93.7

200.7

75

93.8

201

75.1

91

201.2

75.2

94.4

202

75.5

95

203

76

95.5

204

76.4

96

201.8

76.8

961

205

76.83

96.2

205-2

77

96.6

206

77.3

97

206.6

77.6

97.2

207

77.7

97.5

207.5

78

97.7

203

78.2

98

208.4

78.4

98.3

209

78.6

98.7

209.7

79

98.8

210

79.1

99

210.2

79.2

99.4

211

79.5

100

212

80