Escape of liquids through long tubes.—When a liquid passes through a long straight tube, the flow soon diminishes greatly in velocity, because of the friction which takes place between the liquid particles and the walls. If there be any bends or curves in the tube, it is still further diminished by the same cause. The discharge is then much less than it would be from an orifice in a thin wall, and therefore the tube is generally inclined; the liquid then passes down this inclined plane, or it is forced through by pressure, applied at the opposite end.

Direction of the jet from lateral orifices.—From the principle of the equal transmission of pressure, water issues from an orifice in the side of a vessel with the same velocity as from an aperture in the bottom of a vessel at the same depth.

MEASUREMENT OF WATER PRESSURE.

In reference to the [table on the next page], it may be well to say that it has two uses; by it when the “head” is known the pressure can be ascertained to a fraction, thus, Ex. 1, If the head is 140 feet, then the pressure is 60·64 pounds per square inch. Again, Ex. 2, If the pressure is 15·16 per square inch, then the head is 35 feet.

Inside. [(See Page 115.)] Outside.

PRESSURE OF WATER.

The pressure of water in pounds per square inch for every foot in height to 300 feet; and then by intervals, to 1000 feet head· By this table, from the pounds pressure per square inch, the feet head is readily obtained; and vice versa.

Feet Head.Pressure per
square inch.
1 0·43
2 0·86
3 1·30
4 1·73
5 2·16
6 2·59
7 3·03
8 3·46
9 3·89
10 4·33
11 4·76
12 5·20
13 5·63
14 6·06
15 6·49
16 6·93
17 7·36
18 7·79
19 8·22
20 8·66
21 9·09
22 9·53
23 9·96
24 10·39
25 10·82
26 11·26
27 11·69
28 12·12
29 12·55
30 12·99
31 13·42
32 13·86
33 14·29
34 14·72
35 15·16
36 15·59
37 16·02
38 16·45
39 16·89
40 17·32
41 17·75
42 18·19
43 18·62
44 19·05
45 19·49
46 19·92
47 20·35
48 20·79
49 21·22
50 21·65
51 22·09
52 22·52
53 22·95
54 23·39
55 23·82
56 24·26
57 24·69
58 25·12
59 25·55
60 25·99
61 26·42
62 26·85
63 27·29
64 27·72
65 28·15
66 28·58
67 29·02
68 29·45
69 29·88
70 30·32
71 30·75
72 31·18
73 31·62
74 32·05
75 32·48
76 32·92
77 33·35
78 33·78
79 34·21
80 34·65
81 35·08
82 35·52
83 35·95
84 36·39
85 36·82
86 37·25
87 37·68
88 38·12
89 38·55
90 38·98
91 39·42
92 39·85
93 40·28
94 40·72
95 41·15
96 41·58
97 42·01
98 42·45
99 42·88
100 43·31
101 43·75
102 44·18
103 44·61
104 45·05
105 45·48
106 45·91
107 46·34
108 46·78
109 47·21
110 47·64
111 48·08
112 48·51
113 48·94
114 49·38
115 49·81
116 50·24
117 50·68
118 51·11
119 51·54
120 51·98
121 52·41
122 52·84
123 53·28
124 53·71
125 54·15
126 54·58
127 55·01
128 55·44
129 55·88
130 56·31
131 56·74
132 57·18
133 57·61
134 58·04
135 58·48
136 58·91
137 59·34
138 59·77
139 60·21
140 60·64
141 61·07
142 61·51
143 61·94
144 62·37
145 62·81
146 63·24
147 63·67
148 64·10
149 64·54
150 64·97
151 65·40
152 65·84
153 66·27
154 66·70
155 67·14
156 67·57
157 68·00
158 68·43
159 68·87
160 69·31
161 69·74
162 70·17
163 70·61
164 71·04
165 71·47
166 71·91
167 72·34
168 72·77
169 73·20
170 73·64
171 74·07
172 74·50
173 74·94
174 75·37
175 75·80
176 76·23
177 76·67
178 77·10
179 77·53
180 77·97
181 78·40
182 78·84
183 79·27
184 79·70
185 80·14
186 80·57
187 81·00
188 81·43
189 81·87
190 82·30
191 82·73
192 83·17
193 83·60
194 84·03
195 84·47
196 84·90
197 85·33
198 85·76
199 86·20
200 86·63
201 87·07
202 87·50
203 87·93
204 88·36
205 88·80
206 89·23
207 89·66
208 90·10
209 90·53
210 90·96
211 91·39
212 91·83
213 92·26
214 92·69
215 93·13
216 93·56
217 93·99
218 94·43
219 94·86
220 95·30
221 95·73
222 96·16
223 96·60
224 97·03
225 97·46
226 97·90
227 98·33
228 98·76
229 99·20
230 99·63
231 100·06
232 100·49
233 100·93
234 101·36
235 101·79
236 102·23
237 102·66
238 103·09
239 103·53
240 103·96
241 104·39
242 104·83
243 105·26
244 105·69
245 106·13
246 106·56
247 106·99
248 107·43
249 107·86
250 108·29
251 108·73
252 109·16
253 109·59
254 110·03
255 110·46
256 110·89
257 111·32
258 111·76
259 112·19
260 112·62
261 113·06
262 113·49
263 113·92
264 114·36
265 114·79
266 115·22
267 115·66
268 116·09
269 116·52
270 116·96
271 117·39
272 117·82
273 118·26
274 118·69
275 119·12
276 119·56
277 119·99
278 120·42
279 120·85
280 121·29
281 121·72
282 122·15
283 122·59
284 123·02
285 123·45
286 123·89
287 124·32
288 124·75
289 125·18
290 125·62
291 126·05
292 126·48
293 126·92
294 127·35
295 127·78
296 128·22
297 128·65
298 129·08
299 129·51
300 129·95
310 134·28
320 138·62
330 142·95
340 147·28
350 151·61
360 155·94
370 160·27
380 164·61
390 168·94
400 173·27
500 216·58
600 259·90
700 303·22
800 346·54
900 389·86
1000 433·18