lS% Ohjewations on the conJiruEiion of Gates, May 



will be about i\ of an inch only ; for if the hooks and thim- 

 bles are made to fit properly, each hook will not be more 

 than i-i6th part of an inch fmallcr than its thimble ; for as the 

 whole lofs in hanging a gate need not be fo much as i-8th of an 

 inch, or not more perhaps than i-i2th (which exacily balances 

 what is rained in the tliimbles) the extra length of the lower 

 thimble before it is fixed to tlie gate, and that of the lower hook 

 before it is driven into the poii, ought precifely to accord with 

 the dimenfions exprelfed in the plate, fuppofmg the diftance of 

 the two hinges to be 40 inches. 



The diameter of the hooks diould be about i3-i6ths * of an inch, 

 and the perforated parts of the thimbles when made to fit fuch 

 IiQoks will be about 14- :6ths, that is, 7-8ths of an inch diameter : 

 for pivots ot this iize, the above calculations are fuited, as to the 

 velocity of a gate's fall ; and the thimbles fhould be made of 

 rounded iron, that the liiftion maybe reduced by the fmallnefs 

 of the furface to be afiefted thereby f : and when old iron work 

 is made ufe of, wherein a larger furface is expoled to fridlion, 

 I -8th, or i-4th of an inch, as may be fufncient, added to the com- 

 mon extra length of the lower thimble, will be the readieil means 

 of counteracting the extra fridion t. 



F is a complete gate for opening one way, and conflrucled in 

 fuch a m.anner, that it lliall not hnk at the head, as ordinary gates 

 are apt to do. Tlic bars are let into the middle parts of the head 

 and heel, and the lacings are tapered for finifliing upon a level 

 furface with the heel, head, and rail ; as is evident in the follow- 

 ing diredions for the fawing out the timber, which fhould be of 

 kind oak, not too tough ^ and entirely free from fap. 



The warte in planing and fini thing a gate may be allowed for 

 or not, as the gate is defired to be a little more or kfs flrong $. 



Heel 



♦ Thefc dimcnnnns, minute as they may feem, will prefent ro difliculty, 

 rven to an ordinary workman, with the help of a pair of callipers and a common 

 fcale. 



f Sec Mr Vince's experiments " On the Motion of Bodic; affe^led by Fric- 

 •" tion." Vol. LXXV. Philofophical Tranfadions of the Royal Society of 

 London. 



^ If the heel of a gate be not at rijrlit anji^les with the rail, or the perforated 

 part"* of the thimbles be greater than the proportion allowed ior, the deficiency in 

 cither, or both cafes, mull be fupplied by adding to the length of the lower 

 thimble. 



§ When the timber ;=; good, it !■; reduced fo little by being planed and finifhed in- 

 to a gate, that no allowance need be made for the wafte; or, at all events, if the 

 fawcr attends to tlie dimensions recommended, the gate will be quite flrong . c- 

 Bough for its Hzc. 



