46 TABLES 26-28.— GENERAL PHYSICAL CONSTANTS 



Some of the most important results of physical science are embodied in the 

 numerical magnitudes of various universal physical constants. The accurate 

 determination of such constants has engaged the time and labor of many of 

 the most eminent scientists. Some of these constants can be evaluated by 

 various methods. The experiments used to study and measure these constants, 

 in many instances have yielded some function of two or more of the constants 

 (see Table 26) such as h/e, e/m, F/N, h/m, mN , F{e/m), e z /(m/h), etc., 

 rather than the direct value of the constant. Each of the many relations has 

 been investigated by various experimenters at various times, and each investi- 

 gation normally produces a result more or less different from that of any other 

 investigation. Under such conditions there arises a general and continuous 

 need for a searching examination of the most probable value of each important 

 constant. This makes necessary some comparison and analysis of all these ex- 

 perimental data to arrive at the most probable value. An important factor in 

 such work is that there are but few of the constants that do not require for 

 their evaluation a knowledge of certain other constants. These relations are so 

 extensive that most of the physical constants can be calculated from the value 

 of five or six of the selected principal constants and certain ratios. 



Many such critical reviews of these natural constants and conversion factors 

 have appeared in the last 30 to 40 years. The data and discussion given here 

 for the constants and their probable errors are the values arrived at by three 

 physicists, R. T. Birge, 17 J. W. DuMond, and J. A. Bearden, and their associ- 

 ates, who have made some very careful reviews and critical studies of the pub- 

 lished experimental data on these general physical constants and have published 

 several papers giving what they consider as the most probable value. Reference 

 should be made to their original papers for details. 



Birge says in his 1941 paper that as a result of such critical work the situa- 

 tion in respect to these constants has vastly improved over values of about 10 

 years ago, and again one can say that such studies have resulted in more work 

 and thus a more accurate set of constants. 



In 1941 Birge 17 published a very extended list of physical constants and 

 gave calculated values of many other physical constants that depend upon the 

 fundamental constants. Because of the extent of this list, and also because so 

 many of the relations among these constants are given therein, this 1941 list 

 is given here. Almost all these constants in this table (Table 26) are accurate 

 within the limits given. 



DuMond and Cohen 18 prepared a table of some of these constants for the 

 Atomic Energy Commission. A part of this appeared in the July 1953 issue 

 of the Review of Modern Physics. Table 27 gives their values of a number 

 of these physical constants. 



Bearden and Watts 18 " in 1950 made a study of values of a number of physi- 

 cal constants, using some new values in their calculations. They are continuing 

 this work and are now 18b offering some new and more accurate values. Table 

 28 contains their 1950 values (corrected for their newer values) and newer 

 calculated values of some additional constants. 



A comparison of the final values of these fundamental physical constants 

 arrived at by these physicists shows in a real manner the accuracy that may 

 now be claimed. A number of the principal radiation constants were taken 

 from these tables (Tables 26-28) and are given in Table 53. These values 

 have been used for the calculations in the tables in this book since they were 

 available when the work was started and since the newer values would make no 

 practical changes. 



17 Phys. Rev. Suppl., vol. 1, p. 1, 1929; Rev. Mod. Phys, vol. 13, p. 233, 1941; Amer. 

 Journ. Phys., vol. 13, p. 63, 1945. 



18 Phys. Rev., vol. 58, p. 457, 1940; Rev. Mod. Phys., vol. 20, p. 82, 1948. 

 18 * Bearden, J. A., and Watts, H. M., Phys. Rev., vol. 81, p. 73, 1951. 



18b Bearden, Earle, Minkowski, and Thomsen, private communication from J. A. Bear- 

 den. 



SMITHSONIAN PHYSICAL TABLES 



