Jones, H. Spencer (Harold Spencer), 1890- · London E. Arnold & co. · leaf 223
eperformed subsequently at leisure. It is customary then togive on the same plate a short exposure on either side of thestellar spectrum of the spectrum of a terrestrial source, such athe iron arc ; this enables the wave-length of many of the linesin the spectrum under examination to be assigned… … S, S. 105. The Heliotneter.—The hehometer is an instrumentwhich enables the distances apart of neighbouring celestial objects up to a hmit ofabout a couple of de-grees to be measuredwith a very high orderof accuracy. As itsname suggests, it canalso be used for deter-mining the angular dia-meter of…
Astronomy
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