284 A New Table-Stand for Astronomical Telescopes. 



trunnions of the tube. cc, a pah* of steadying — or rather 

 elevating-rods, half an inch thick, having eyes at their ends ; 

 those at the upper ends receive the foremost trunnions, d d, 

 two inclined planes of mahogany secured to the board, rising 

 1| inch, and about 10 inches long ; along the tops of these are 

 rounded ridges of brass, accurately straight and smooth, to act 

 as guides, e e, two little travellers of box-wood, grooved 

 beneath to slide along the guides, ff, a bent rod of |- brass 

 (hollow for lightness), which passes through and fits tight in 

 the travellers, connecting them together ; its extremities project 



Fia. 2. 



like the axle-arms of a carriage, and on them work the lower 

 eyes of the elevating rods. g g, a screw 10 inches long 

 (about 20 turns to the inch). It passes through the bent rod 

 //, working in a nut attached to its middle, h, a milled head 

 on the screw, and a little winch or handle, which can be 

 removed at pleasure. The screw turns in a bearing fixed to 

 the stand at h. 



This completes tho mechanism for altitude. That for 

 azimuth is very simple, and consists merely of two little well- 

 turned rollers or wheels, r r, fixed to the stand beneath, and 



