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Portland flone, fo placed as not to touch the pillars or floor ; 

 this is to fupport the vertical axis. C reprefents the clock 

 pillar, being five feet fquare at the bafe, decreafing as it rifes 

 to two feet above, in order to afford all proper ftability. This 

 may appear to fome perhaps rather whimfical than neceffary ; 

 but it vsrould not be difficult to lliew, both from theory and 

 experiment, the ncceffity of the moft folid fupport for a clock, 

 on which, according to the modern pradice, fo much juftly 

 depends. Befides, there is a proper degree of attention due on our 

 part to the work of Mr. Arnold, whofe reputation in fomc degree 

 lies at the mercy of every one who may or may not be induced 

 to give to his fuperior work every minute attention which it 

 requires and deferves. Our clocks, executed by him, are finiflied 

 in a mafterly manner, the pallets of ruby, all the holes of the 

 laft movement jewelled, the fufpenfion fprings of gold, with 

 his own five-barred pendulum, with cheeks capable of experi- 

 mental adjuftment, fo as to prove all vibrations ifochronal, what- 

 ever be the throw out of the clock. 



The floor of the room is framed fo as to let all thefe pillars 

 rife totally detached from it. A few inches above the floor, 

 around each pillar, is a wooden flcirting, terminated by pliable 

 leather, which reaches to the floor, and overhangs a moulding 

 raifed about each pillar. This is done to prevent the admiflion 



of 



feems to promife many advantages in temperature both of air and inftrument, 

 facility and accuracy of adjuftmsnt, not to mention the certainty of being enabled 

 to prove the centre of the inftrument -, but on this I fhall not at prefent 

 enlarge 



