Mechanics of the Household / A Course of Study Devoted to Domestic Machinery and Household Mechanical Appliances

by E. S. Keene

The popular conception of the hot-air furnace method of heating is that it produces particularly dry air, when in reality it is the only type of house-heating plant in which any provision is made for adding water to the air. These furnaces are usually furnished with a water reservoir by use of which the humidity may be raised to a desirable point.

Much of the water which enters the air of the average home, during winter weather, comes from the evaporation that goes on in the kitchen. Usually on wash days the humidity is raised to a marked degree and that day is commonly followed by a short period of agreeable atmospheric condition. The arrangement of many houses is such that a much-improved condition of humidity might be obtained from the kitchen by continuous evaporation of water from a tea-kettle.

Relative Humidity
Depression of wet-bulb thermometer (t-t')

Air temp. t	1.0	2.0	3.0	4.0	5.0	6.0	7.0	8.0	9.0	10.0
35	91	82	73	64	55	46	37	29	20	12
36	91	82	73	65	56	48	39	31	23	14
37	91	83	74	66	58	49	41	33	25	17
38	91	83	75	67	59	51	43	35	27	19
39	92	84	76	68	60	52	44	37	29	21
40	92	84	76	68	61	53	46	38	31	23
41	92	84	77	69	62	54	47	40	33	26
42	92	85	77	70	62	55	48	41	34	28
43	92	85	78	70	63	56	49	43	36	29
44	93	85	78	71	64	57	51	44	37	31
45	93	86	79	71	65	58	52	45	39	33
46	93	86	79	72	65	59	53	46	40	34
47	93	86	79	73	66	60	54	47	41	35
48	93	87	80	73	67	60	54	48	42	36
49	93	87	80	74	67	61	55	49	43	37
50	93	87	81	74	68	62	56	50	44	39
51	94	87	81	75	69	63	57	51	45	40
52	94	88	81	75	69	63	58	52	46	41
53	94	88	82	75	70	64	58	53	47	42
54	94	88	82	76	70	65	59	54	48	43
55	94	88	82	76	71	65	60	55	49	44
56	94	88	82	77	71	66	61	55	50	45
57	94	88	83	77	72	66	61	56	51	46
58	94	89	83	77	72	67	62	57	52	47
59	94	89	83	78	73	68	63	58	53	48
60	94	89	84	78	73	68	63	58	53	49
61	94	89	84	79	74	68	64	59	54	50
62	94	89	84	79	74	69	64	60	55	50
63	95	90	84	79	74	70	65	60	56	51
64	95	90	85	79	75	70	66	61	56	52

Air temp. t	11.0	12.0	13.0	14.0	15.0	16.0	17.0	18.0	19.0	20.0
35	4
36	6
37	9	1
38	12	4
39	14	7
40	16	9	2
41	18	11	5
42	21	14	7	0
43	23	16	9	3
44	24	18	12	5
45	26	20	14	8	2
46	28	22	16	10	4
47	29	23	17	12	6	1
48	31	25	19	14	8	3
49	32	26	21	15	10	5
50	33	28	22	17	12	7	2
51	35	29	24	19	14	9	4
52	36	30	25	20	15	10	6	0
53	37	32	27	22	17	12	7	3
54	38	33	28	23	18	14	9	5	0
55	39	34	29	25	20	15	11	6	2
56	40	35	31	26	21	17	12	8	4
57	41	36	32	27	23	18	14	10	5	1
58	42	38	33	28	24	20	15	11	7	3
59	43	39	34	30	25	21	17	13	9	5
60	44	40	35	31	27	22	18	14	10	6
61	45	40	36	32	28	24	20	16	12	8
62	46	41	37	33	29	25	21	17	13	9
63	47	42	38	34	30	26	22	18	14	11
64	48	43	39	35	31	27	23	20	16	12

Relative Humidity (Continued)
Depression of wet-bulb thermometer (t-t´)

Air temp. t	1.0	2.0	3.0	4.0	5.0	6.0	7.0	8.0	9.0	10.0	11.0
65	95	90	85	80	75	70	66	62	57	53	48
66	95	90	85	80	76	71	66	62	58	53	49
67	95	90	85	80	76	71	67	62	58	54	50
68	95	90	85	81	76	72	67	63	59	55	51
69	95	90	86	81	77	72	68	64	59	55	51
70	95	90	86	81	77	72	68	64	60	56	52
71	95	90	86	82	77	73	69	64	60	56	53
72	95	91	86	82	78	73	69	65	61	57	53
73	95	91	86	82	78	73	69	65	61	58	54
74	95	91	86	82	78	74	70	66	62	58	54
75	96	91	87	82	78	74	70	66	63	59	55
76	96	91	87	83	78	74	70	67	63	59	55
77	96	91	87	83	79	75	71	67	63	59	56
78	96	91	87	83	79	75	71	67	64	60	57
79	96	91	87	83	79	75	71	68	64	60	57
80	96	91	87	83	79	76	72	68	64	61	57
82	96	92	88	84	80	76	72	69	65	62	58
84	96	92	88	84	80	77	73	70	66	63	59
86	96	92	88	85	81	77	74	70	67	63	60
88	96	92	88	85	81	78	74	71	67	64	61
90	96	92	89	85	81	78	75	71	68	65	62
92	96	92	89	85	82	78	75	72	69	65	62
94	96	93	89	86	82	79	75	72	69	66	63
96	96	93	89	86	82	79	76	73	70	67	64
98	96	93	89	86	83	79	76	73	70	67	64
100	96	93	90	86	83	80	77	74	71	68	65
102	96	93	90	86	83	80	77	74	71	68	65
104	97	93	90	87	84	80	77	74	72	69	66
106	97	95	90	87	84	81	78	75	72	69	66
108	97	93	90	87	84	81	78	75	72	70	67

Air temp. t	12.0	13.0	14.0	15.0	16.0	17.0	18.0	19.0	20.0
65	44	40	36	32	28	25	21	17	13
66	45	41	37	33	29	26	22	18	15
67	46	42	38	34	30	27	23	20	16
68	47	43	39	35	31	28	24	21	17
69	47	44	40	36	32	29	25	22	19
70	48	44	40	37	33	30	26	23	20
71	49	45	41	38	34	31	27	24	21
72	49	46	42	39	35	32	28	25	22
73	50	46	43	40	36	33	29	26	23
74	51	47	44	40	37	34	30	27	24
75	51	48	44	41	38	34	31	28	25
76	52	48	45	42	38	35	32	29	26
77	52	49	46	42	39	36	33	30	27
78	53	50	46	43	40	37	34	31	28
79	54	50	47	44	41	37	34	31	29
80	54	51	47	44	41	38	35	32	29
82	55	52	49	46	43	40	37	34	31
84	56	53	50	47	44	41	38	35	32
86	57	54	51	48	45	42	39	37	34
88	58	55	52	49	46	43	41	38	35
90	59	56	53	50	47	44	42	39	37
92	59	57	54	51	48	45	43	40	38
94	60	57	54	52	49	46	44	41	39
96	61	58	55	53	50	47	45	42	40
98	61	59	56	53	51	48	46	43	41
100	62	59	57	54	52	49	47	44	42
102	63	60	57	55	52	50	47	45	43
104	63	61	58	56	53	51	48	46	14
106	64	61	59	56	54	51	49	47	45
108	64	62	59	57	54	52	50	47	45