458 PROCEEDINGS OF THE AMERICAN ACADEMY. 



mostly large forks, while the A forks were the ordinary musicians' small 

 A3 tuning forks, tuned by the authors to convenient pitches. The same 

 forks were used for several years subsequent to 1880. 



In the recent measurements three large standards of Koenig have been 

 used as a basis, viz.: a C3 of 256 double vibrations, a tempered C3 of 

 258. G5 vibrations, and an A3 of 435 vibrations, at a standard temperature 

 of 20° C. From these were rated by the method of beats, a series of 

 large Co forks and also two sets of C4 small Scheibler's tonometer forks 

 by Koenig, and two sets of A3 forks of the same character. These small 

 tonometer forks were also compared with a series of large Scheibler 

 tonometer forks by Koenig, which last were assumed to be correct within 

 the limits sought in our measurements. 



Table II. gives the results of ratings of various standards of epochs 

 indicated by the date. In all measurements later than 1891 the Koenig 

 standard tonometer forks have been employed. The data given in 

 Table II. are all in terms of the pitches of C4 and A3. The pitch of the 

 standards actually measured is specifically stated in all cases except when 

 it is C4 or A3. 



Table III. contains the results of measurements of fifty-six forks sent 

 by various manufacturers to the Committee of the National Piano and 

 Organ Manufacturers' Association in response to their request already 

 referred to. A preliminary rating was made by me in 1890-91 with 

 such forks as I then possessed. The results of this were shown in a 

 circular privately printed in 1891 for the use of members of the Associa- 

 tion. A more exact determination was made by me a few months later 

 in 1891, using the Koenig tonometer forks as previously stated. The 

 results of these measurements are found in the table. 



Certain of the forks and other standards referred to in Table II. 

 deserve special mention. Those numbered 4, 5, 6, 7, 9, 10, 11, 12, 13, 

 14, 15, 16, 17, 18, 19, 87, 88 were intended to give the physical pitch. 

 Nos 2 and 3 had been in the possession of their owners for many years, 

 and were authenticated as to the date assigned to them. Nos. 5 and 6 

 are two forks belonging to Harvard University, imported many years 

 since. No. 5 is of the early Marloye pattern, with inclined prongs, but 

 does not bear any mark to indicate the maker. No. 6 bears the mark 

 " R. K.," always employed by Koenig. Nos. 16 and 17 are also Koenig 

 forks of early date, belonging to Harvard University. No. 8 is a pitch 

 pipe formerly employed for church use, belonging to Mr. B. J. Lang of 

 Boston. It is a whistle with a movable plug, and the pitch can be varied 

 through an octave. When the plug is set for C4, according to the lines 



