PREFACE TO THE NINTH REVISED EDITION 



This edition of the Smithsonian Physical Tables consists of 901 tables giv- 

 ing data of general interest to scientists and engineers, and of particular inter- 

 est to those concerned with physics in its broader sense. The increase in size 

 over the Eighth Edition is due largely to new data on the subject of atomic 

 physics. The tables have been prepared and arranged so as to be convenient 

 and easy to use. The index has been extended. Each set of data given herein 

 has been selected from the best sources available. Whenever possible an expert 

 in each field has been consulted. This has entailed a great deal of correspond- 

 ence with many scientists, and it is a pleasure to add that, almost without 

 exception, all cooperated generously. 



When work first started on this edition, Dr. E. U. Condon, then director of 

 the National Bureau of Standards, kindly consented to furnish any assistance 

 that the scientists of that institution were able to give. The extent of this help 

 can be noted from an inspection of the book. Dr. Wallace R. Brode, associate 

 director, National Bureau of Standards, gave valuable advice and constructive 

 criticism as to the arrangement of the tables. 



D. H. Menzel and Edith Jenssen Tebo, Harvard University, Department of 

 Astronomy, collected and arranged practically all the tables on astronomy. 



A number of experts prepared and arranged groups of related data, and 

 others either prepared one or two tables or furnished all or part of the data 

 for certain tables. Care has been taken in each case to give the names of those 

 responsible for both the data and the selection of it. A portion of the data was 

 taken from other published sources, always with the. consent and approval of 

 the author and publisher of the tables consulted. Due credit has been given in 

 all instances. Very old references have been omitted. Anyone in need of these 

 should refer to the Eighth Edition. 



It was our intention to mention in this preface the names of all who took part 

 in the work, but the list proved too long for the space available. We wish, 

 however, to express our appreciation and thanks to all the men and women 

 from various laboratories and institutions who have been so helpful in con- 

 tributing to this Ninth Edition. 



Finally, we shall be grateful for criticism, the notification of errors, and 

 new data for use in reprints or a new edition. 



W. E. FORSYTHE 

 Astrophysical Observatory 

 Smithsonian Institution 

 January 1951 



EDITOR'S NOTE 



The ninth edition of the Physical Tables was first published in June 1954. 

 In the first reprint (1956), the second reprint (1959), and the third (1964) 

 a few misprints and errata were corrected. 



in 



