PEIRCE. — TIME OF CONTACT ON A TELEGRAPH KEY. 



99 



the average length of all the contacts, and also the average length of 

 the half of the whole number which were shortest. I am indebted to 

 Mr. John Coulson for help in making the observations. 



The recorded averages are given in ten thousandths of a second, but 

 of course the average of two long sets of trials made by the same per- 

 son would not agree exactly. There is, however, in most cases, a 

 striking agreement between observations made at different times by 



TABLE n. 



one observer, and except in the cases of two persons whose records at 

 the beginning were not very good, practice did not shorten the time 

 appreciably. In my own case the shortest average that I have been 

 able to get differs from my longest by about one sixth part of the latter. 

 Tli£ records of thimble contacts made by two persons were 0.0036 

 and 0.0083 seconds in November, and 0.0037 and 0.0083 seconds in 

 January. 



Table I shows results obtained with the telegraph key, and, though 

 the range is large, it appears that, when the key must be lifted away 



