138 ..s: !Description and Use of the

PROBLEM XXL

The sun’s altitude, as observed witha terrestrial or visible horizon.

226. The altitude of the sun is greateror less, according as one of the parallel rightlines or rays, coming from the fun to us, isfarther from, or nearer to, our horizon.

Apply the terrestrial horizon to London,the fun being supposed in the zenith, or onthe ceiling directly over the globe.

If then from London a line pass verti-cally upwards, the fun* will be seen fromLondon in that line.

At fun-rifing, when London is broughtto the west edge of the broad paper circle,the supposed line will be parallel to the ter-restrial horizon, and from London will bethen seen in the horizon.

As the globe is gradually turned fromthe west towards the east, the horizon willrecede from the line which passes perpen-dicularly upwards; for the line in whichthe fun was then seen, seems to glide far-ther and farther from the terrestrial horizon ;that is, the fun’s altitude increases as gra-dually