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LIX. On the Determination of the Acceleration of Gravity for 

 Tokioj Japan, 



To the Editors of the Philosophical Magazine and Journal. 



Gentlemen, 



MY attention has been directed to a paper in your Journal 

 for April, on the " Determination of the Acceleration 

 of Gravity for Tokio, Japan," which I am sorry to see con- 

 tains a considerable proportion of questionable teaching. As 

 the subject is attracting a good deal of attention abroad, I am 

 unwilling to allow this to pass muster as a fair representation 

 of English acquaintance with it. Neither is it pleasant to think 

 that the youth of Japan are being enlightened in this way 

 regarding a pursuit in which England was once foremost. 



To any one acquainted with the history and literature of 

 pendulum experimentation, it is patent that the teachers in 

 this case are either entirely unacquainted with both, or hold 

 the opinion that the first canon of "original research" is to 

 avoid all study of previous work. As it is more pardonable 

 to hold a heterodox opinion than to be ignorant, I am willing 

 to attribute the originality in this paper to such a source — the 

 more so as the concluding sentences seem to point to such a 



a doctrine. The writers say, " that this investigation 



has resulted from the plan we have followed of teaching the 

 laboratory students not, as is customary in colleges, to repeat 

 well-known experiments, but to endeavour in their investiga- 

 tions to advance, in some small degree at any rate, the bounds 

 of existing knowledge." 



The doctrine is as erroneous as the design is laudable. But 

 I must say that the teaching as here in evidence has followed 

 the lines laid down only too well ; and if I could believe that 

 the absence of all indication of a knowledge of previous expe- 

 riments is feigned — if the mistakes are not genuine — if the 

 oversights are intentional — then the authors of this account 

 have done themselves great injustice in publishing this instance 

 of their method of instigating to original research. 



" To repeat well-known experiments " slavishly and un- 

 comprehendingly is no doubt undesirable ; but it is far more 

 undesirable to neglect the commonest and most essential prin- 

 ciples of exact experimentation, in favour of abstruse investi- 

 gation of conditions which, almost obviously, are unimportant. 

 I will give a single extract to show that I am not making a 

 random charge: — 



" The two most obvious corrections to apply to this result 

 [the time of vibration of a pendulum in air] are the correc- 

 tions for infinitely small arcs and for the air-friction — neither 



