HOROLOGY. 



169 



round the barrel. This .080 multiplied by 10', the num- 

 ber of turns proposed, will give 1.S8 inch, or very near 

 1 inch and T Vths of an inch for the length of the bar- 

 rel between the ends. The barrel, or great wheel, mak- 

 ing a revolution in 48 hours, we must see what the 

 number of teeth for it, and the second wheel pinion 

 which it drives, ought to be, and likewise the number of 

 teeth for the second wheel, and that of the centre pi- 

 nion, so that this last shall make 48 turns for one of the 

 great wheel. Let us assume 24 for the number of the 

 second wheel pinion, and 20 for that of the centre pi- 

 nion. If we take 6 times 24 for the number of the 

 great wheel teeth, and 8 times 20 for the number of 

 teeth in the second wheel, then the centre pinion will 

 be turned 48 times round for once of the great wheel, 

 as 6 X 8=48. Having assumed the pinions to be 24 

 and 20, these multiplied into one another, and the pro- 

 duct multiplied by 48, the last product will be such a 

 number, as when divided by a number for one wheel, 

 the quotient will be a number for another wheel, 

 24 X20=48OX 48=23040, which divided by 144, the 

 number for one wheel, the quotient will be 1 60 for the 

 number of teeth of the other wheel Or if we take 25 

 for the number of the second wheel pinion, and 20 for 

 the other, these multiplied together, and the product 

 again by 48, will give such a number, as when divided 

 >, the number for one wheel, the quotient will be 

 160 for the number of the other wheel, 25 x 2O=500 x 

 48 =24000 -=-150= 160. The numbers for the teeth of 

 these wheels may be obtained in the same way which we 

 make use of to find the number* of the teeth of the 

 whreli for dock and watch movements. It" we take 26 

 for the second wheel pmion, and for the centre piniaw, 

 and multiply them into one another, and if the product 

 is again multiplied bjr **, the number of tarns of the 

 centre pinion for one of the great wheel, we shall have 

 a number, which being subdivided till there u no re- 

 mainder, its multiple* will farm such sets of numbers as 

 may be given for the teeth of the two wheels. Thus 

 26x20=520X48=24960, the multiples of which will 

 be seven '/, one 3, one 5, ami I . t, which give the num- 

 bers 156 and 160 for the wheel*. For the subject of 

 our astronomical clock, we shall adopt the number 144 

 for the great wheel, and 1 60 for the second wheel, and 

 in pinion 2V, and SO for the centre wheel The object 

 is U> have as high numbered wheels and pinions as am 

 be conveniently got in. The diameter of the great 

 wheel h iinmnrTto be such, as will allow the teeth 

 proposed for it to have strength timusjh to bear the ex- 

 ertion pot upon them, which we snafl take at 3.580, and 

 for that of the second wheel S.3OO. In other words, 

 these are 3.5 inches, and .0 part* more of an 

 inch, and 3.3 inche* for the other. The pmion* for the 

 third and swing wheels are to be 16 each, the number 

 of teeth for the ctnire wheel 1*8, and for the third wheel 

 190, For the sake of savuigtroid>U to those who may 

 be inclined to make Mca a dack, we shall give the dia- 

 meters of the wheek and pmion*, and the distance of 

 their < 



The great wheel 

 cMcond wheel . 



wheel . . 

 Third wheel . . 

 Swing wheel . . 



Mo 



128 



HP 



30 



Mr. of Centra. PMse. tar. 

 90*0 2021.7 24 614 

 3300 1830 90 437-8 

 9800 I4S7.2 16 349.3 

 2300 itftO 16 9*9 

 MM 



Wheel concentric") 

 with the second > 

 ditto J 



Wheel carrying 7 



Teeih. 



the hour hand 



20 



60 



D i. line- 

 ttr. 



743.6 

 20325 



Atronomi- 

 Distance c ,i Clocks. 

 of Centre. -_-_ _- 



The wheel of 20 is concentric with the second wheel, 

 which making three revolutions in 24 hours, carries 

 the hourhand- wheel of 60 once round in that time. 

 The hour circle will have the 24 hours marked on it, 

 that is, from 1 to 21, being intended for a side- 

 real time clock. There is no other dial-work than the 

 wheels of 20 and <x>. which will require to have the 

 hour-hand turned about by itself,* when at any time the 

 clock is set by the minute hand. From the centre of 

 the dial to the centre of the hours and seconds circles, is 

 '2.5 inches to each. The centre of the great wheel is 

 on a line below the centre of the dial about 1 inch, 

 and to the left of the perpendicular line, in the centre 

 of the dial, '_'.'' inches. The centre of the third wheel 

 is also to the left of this line, a little more than half an 

 inch, say _5lf) of an inch. The 'scapement we would 

 propose to be the same as those whieh we have made 

 to astronomical clocks, after the principle of that of 

 Mudge's time-keepers ; only the pallets might be made 

 longer, and the springs of course a little stronger. The 

 angle of 'scapement might be reduced to I. 1 , minute- 

 on each aide of the point of rest, and yet the pendulum 

 may be made to vibrate about 1.5 degrees on each side. 

 The unlocking here would be as near the lowest point 

 a* possible, or when the pendulum had its maximum 



OffCst* 



( HAP. XV. 

 On (Mmet and BtUt. 



(HIKE, in iu general meaning, is applied t.. the On rliimtt 

 sounding of bells, such as change-ringing by church snd belli, 

 bells, or the striking quarters of the hour by a clock <>n 

 two or more bells, or to tune* played by a clock on 

 a aerie* of nine, twelve, or sixteen bells, tuned to 

 their respective note* on the Male. Clock* that play 

 tune* on bell* are called musical clock* ; when hour 

 quarter* are chimed or struck by the clock itself, fix- 

 example, on six or on eight bells in octave, it i called 

 a quarter clock, and sometimes a chime clock ; and 

 when the quarter* are (truck by a string being pulled, 

 it is called a pull quarter or a repeating clock, whether 

 the quarter* are (truck on six or eight bells, or whe- 

 ther they are given by a double blow on the hour-bell, as 

 in the repeating watch. A time piece, or going part, and 

 having no hour striking part, but having a repeating 

 part, M by some called a silent pull. 



Various way* may be adopted for pricking tune* on Method of 

 the music barrel* of clock*. The earlier mode of do- pricking 

 ing this was by taking a piece of writing paper of such '" nc * ". 

 a aia* a* to cover exactly the surface of the liarrel, br r ^ 

 and in a direction perpendicular to the axis of the bar- r | IB3 

 rel, to draw as many lines parallel to one another a* 

 there were note* in the tune to be laid down on the 

 barrel, the lines being equidistant, and correspond- 

 ing perfectly with the hammer tails as they stood in 

 the hammer frame. They were marked at each end 



I ( IBOS* who wish lo hire the matt perfect mechanism (or u* dial-work. 



Y 



I 



