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XIII. " Report of Proceedings of the Astronomical Expedition 

 to Teneriffe, in 1857." By Prof. C. PIAZZI SMYTH. Pre- 

 sented by G. B. AIRY, Esq., F.R.S., Astronomer Royal. 

 Received June 2, 1857. 



(Abstract.) 



The Report, presented originally to tbe Admiralty, at whose ex- 

 pense and whose orders the Expedition was sent out, consists of ten 

 parts, with their contents as follows : 



Part 1 . Astronomical and Physical observations. 



Part 2. Mountain Meteorological Journal. 



Parts. Reductions of above. 



Part 4. Sea-level Meteorological Journal. 



Part 5. Reductions of above. 



Part 6. Plans, Sections, and Astronomical illustrations. 



Parts 7> 8, 9. Condensed statement of results and conclusions in 

 Astronomy, Physics, Meteorology, Geology, Botany, and Navigation. 



Part 10. Photographs illustrating the botany and geology of three 

 different levels in the Island. 



The original instructions of Prof. Piazzi Smj-th had been purely 

 astronomical, and were to ascertain how much telescopic vision could 

 be improved by eliminating the lower third of the atmosphere. In 

 furtherance of this view, he erected tbe Sheepshanks equatorial of 

 the Edinburgh Observatory on Mount Guajara in Teneriflfe at a 

 height of 8903 feet, and found the space-penetrating power ex- 

 tended from mag. 10 to mag. 14, and so great an improvement in 

 definition, that a magnifying power of 240 could be used with more 

 satisfaction on the mountain, than one of 60 in Edinburgh. After 

 a month's experience of this station, he ascended to a higher one 

 the Alta Vista at a height of 10,702 feet on the eastern slope of 

 the Peak, and there erected the large equatorial of Cooke, lent for 

 the occasion by Mr. Pattinson of Newcastle. The definition was here 

 admirable, and the telescope equal, if not superior, to all the test 

 objects it was turned upon. A comparative hypsometric estimate 

 was not possible; for although the observer had spent an equal 

 number of days to what he employed on the Peak, in trying to as- 

 certain the capabilities of the instrument at the house of its hospi- 



