354 Scientific Proceedings, Royal Dublin Society. 
The ordinary slow motion arrangements employed for the 
purpose are subject to some disadvantages. 
If they be of the forms of tangent screws they are lable to loss 
or “back lash,” and their action is limited. If they be of the 
form of epicyclic wheels they necessitate the introduction of 
several additional wheels into the clock train, and thus injure 
the perfection of uniformity of motion. 
The new form (Figs. 4 and 5) is free from all these defects. 
Any portion of the shaft ss’ connecting clock to endless screw, 
which drives A sector, is cut across, one portion being let into 
the other for steadiness, and on the extreme inner ends of each 
of the shafts ss’ are keyed or fastened toothed wheels WW’, one of 
these wheels having fifty-four and the other fifty-six teeth, or any 
other convenient numbers (these are preferred as being propor- 
tioned to the siderial and lunar time, which is convenient for 
obvious reasons). A pulley wheel P, with groove on its edge, 
plays freely round one of the axis in juata position to the two 
toothed wheels—on this pulley wheel is fixed a stud or pin (@), 
on which is strung a pinion, the teeth of which pinion gear 
into both the fifty-four and fifty-six wheels. 
