1:2 I). Todd — Open- Air Telescope. 



double-slide plateholder with independent rotary motion, 

 mieroinetric work and oven precision photography might be 

 quite practicable. All the clamps and motions and clocks may 

 be controlled by electric motors operated from triplicate switch- 

 boards in (1) the observing box, ('2) the altitude house (not 

 shown on the upright piers), and (3) from the azimuth room 

 concealed beneath the basal drum. 



In lieu of observing-chair or rising-floor, observer and assist- 

 ant ride in a light carriage on the eye-end, swinging on a 

 horizontal ball-bearing axis which passes through the focal 

 plane. This may be wholly enclosed for weather protection, 

 and it can readily be warmed electrically in winter. Should 

 such an instrument ever be erected on a high mountain, as for 

 instance, Fuji-yama in Japan, 12,400 feet elevation, where a 

 saddle within the crater provides an ideal location such that 

 wind would rarely shake the telescope, it would be wholly 

 feasible, in fact very easy, to supply the observing-box with 

 air artificially compressed to sea-level tension. Thereby we 

 should avoid the disastrous effect of mountain sickness, which 

 not only interferes greatly with one's comfort at elevations 

 much in excess of 10,000 feet, but in consequence of the 

 quickened pulse, tends to shorten the life-span of anyone who 

 persists in tarrying long at great elevations, without frequent 

 return to safe and lower altitudes. 



Only the open-air alt-azimuth is discussed in the present 

 paper. On the successful construction of such an instrument. 

 an equatorial of similar type would be found easy to design 

 and construct on a mountain side sloping poleward. The best 

 design would be a lengthened polar axis, with adequate flota- 

 tion drums near each end, and a forked overhanging head, 

 very similar to the alt-azimuth design here given, only more 

 strongly braced, and in which no added weight is requisite for 

 declination counterpoise. 



Observatory : Amherst College. 

 April 22, 1911. 



