41 



I think I may assure you that not many weeks will elapse 

 until Boston will offer this same advantage to the ships 

 within her harbpr. 



I have mentioned the time-ball first, because it has 

 secured for itself a wide recognition as the simplest way 

 of announcing an arbitrary instant of time. But like the 

 newspaper dropped at the door, or the water which flows 

 upon turning the faucet, the simple result attained in the 

 dropping of a time-ball is the out-growth of the most 

 refined principles of mechanism, and is the product of 

 skilful assiduity on the part of the astronomer. It is our 

 province now to ask these questions, "Where do we get 

 and how do we keep our time?" These questions come 

 with force at the moments when we stand looking alter- 

 nately at the face of our watch, and the rear platform of 

 a departing train ; or when the Gold Stock Exchange 

 closes one minute before we thought it would ; or when 

 some majestic steamer wrecks in a fog on our coast 

 because her chronometers are at fault. 



We all know that whatever may be the merits of our 

 sun in other respects he is not a very accurate marker of 

 the length of a clay. Thus February 10th, he is fifteen 

 minutes slow of any respectable clock, and then he catches 

 up until the middle of May, when he is four minutes fast. 

 July 25th, again, he is six minutes slow, and November 

 2nd, he crosses the meridian sixteen minutes before 

 twelve. From time immemorial, however, the sun has 

 marked the beginning of the day's labor, and in order to 

 overcome the difficulties in measuring the length of a day, 

 caused by the sun's irregularity, astronomers imagine that 

 there exists in the heavens a fictitious sun, which moves 

 uniformly along the Equator of the heavens. Four times 

 in the course of a year the fictitious sun and the real sun 

 indicate the same clock time. I shall point out to you 



