70 ROUGH WA YS MADE SMOOTH. 



sary skill), gives the value, 92,250,000 miles. From this it 

 may fairly be concluded that Newcomb's mean value, which 

 has in fact been accepted by all American and Continental 

 astronomers, is certainly within 600,000 miles, and most 

 probably within 300,000 miles of the true mean distance of 

 the sun. 



But now, to revert to our illustrative case, let us suppose 

 that after passing the windows of six or seven horologists, 

 from whose clocks we have obtained such satisfactory 

 evidence as to the probable hour, we bethought ourselves 

 of a place where, from what we had heard, a still more exact 

 determination of the hour might be obtained. While still on 

 the way, however, we learn from a friend certain circum- 

 stances suggesting the possibility that the clocks at the place 

 in question may not be so correct as we had supposed. 

 Persisting, however, in our purpose, we arrive at the place, 

 and carefully compare the indicati ns of the various clocks 

 there with the time indicated by our watch, corrected (be it 

 supposed) in accordance with the results of our former obser- 

 vations. Suppose now that the hour indicated by the various 

 clocks at this place, instead of agreeing closely with that 

 which we had thus inferred, differs from it by fully half a 

 minute. Is it not clear that instead of being led by this 

 result to correct our former estimate of the probable hour, 

 we should at once infer that the doubts which had been 

 suggested as to the correctness of the various clocks at this 

 place were fully justified ? The evidence of the other sets 

 of clocks would certainly not be invalidated by the evidence 

 given by the set last visited, even if the accuracy of these 

 had not been called in question. But if, as supposed, some 

 good reason had been given for doubt on this point, as for 

 instance, that of late the supervision of the clocks had been 

 interrupted, we should not hesitate for a moment to reject 

 the evidence given by these clocks, or at least to regard it as 

 only tending to demonstrate what before we had been led to 

 surmise, namely, that these clocks could not be relied upon 

 to show true time. If however, furthermore, we found, not 



