Velocity of circulating- "water -=ft. per sec. '~^1\ Geo. A. Orrok, in Journal American Society of Mechanical Engineers

Fig. 163. Relation of the Rate of Heat Transmission to the Velocity of the Circulating Water in Surface Condensers

Correlation charts of this type have sometimes been called "shot-gun diagrams " The investigator makes a dot for each observation recorded, and then judges from the arrangement of the dots whether there is any general law expressing a relation between the two variables studied

Curves like those seen in Fig. 163 may be sketched in free-hand, or they may be much more conveniently drawn by using the irregular or so-called "French curves" which may be obtained in any store selling drafting instruments or artists' materials. As it frequently happens that an irregular curve available does not exactly fit the dots through which the curve line is to be drawn, care must be taken to

GRAPHIC METHODS

shift the irregular curve along and draw only short portions of the curve line at any one stroke of the pencil or pen. Care in shifting the irregular curve will permit drawing a clean, smooth curve line, even though the irregular curve used is quite different in shape from the curve line which is drawn.

•

o^

-^

-^

^

^0

■ 9

^

^

ea

^

--

o

Z^

^(b

^o

^^

-'

52 63 54 55 56 57 59 59 60 61 62 63 64 6S 66 67 60 69 70 71 7e

Noiher't Span (=1/) in Inches.