Attempt to ascertain Date of Stonelienyc from its Orientation. 137 



images of neighbouring stars of equal magnitude. This peculiarity of 

 the Nova's disc was first remarked by Flammarion and Antoniadi, and 

 later by Max Wolf, Kostinsky, and von Gothard. It owes its origin 

 probably to the exceptionally strong ultra-violet rays emitted by the 

 Nova, which are not brought to the focus for which the objective is 

 corrected. 



The recent photographs have been taken by Mr. Butler and 

 Mr. Kolston. The visual observations have chiefly been made by 

 Messrs. Fowler and Butler. Mr. Baxandall has undertaken the 

 reduction to wave-lengths and the discussion of the lines in the photo- 

 graphic spectrum, while Dr. Lockyer and Mr. Baxandali have assisted 

 in the preparation of the present paper. 



" An Attempt to ascertain the Date of the Original Construction 

 of Stonehenge from its Orientation." By Sir NORMAN 

 LOUKYER, K.C.B., F.R.S., and F. 0. PENROSE, F.E.S. Received 

 October 21, 1901. 



This investigation was undertaken in the spring of the present year, 

 as'a sequel to analogous work in Egypt and Greece, with a view to deter- 

 mine whether tfhe orientation theory could throw any light upon the 

 date of the foundation of Stonehenge, concerning which authorities vary 

 in their estimate by some thousands of years. We beg to lay before the 

 Royal Society the results derived from a careful study of its orienta- 

 tion for the purpose of arriving at the probable date of its foundation 

 astronomically. This is not, indeed, the first attempt to obtain the 

 date of Stonehenge by means of astronomical considerations. In Mr. 

 Godfrey Higgins' work* he refers to a method of attack connected 

 with precession. This furnished him with the date 4000 B.C. 



More recently, Dr. W. M. Flinders Petrie,f whose accurate plan is a 

 valuable contribution to the study of Stonehenge, was led by his 

 measures of the orientation to a date very greatly in the opposite 

 direction, but, owing to an error in his application of the change of 

 obliquity, clearly a mistaken one. 



As the whole of the argument which follows rests upon the assump- 

 tion of Stonehenge having been a solar temple, a short discussion of 

 the grounds of this view may not be out of place ; and, again, as the 

 approximate date which we have arrived at is an early one, a few 

 words may be added indicating the presence in Britain at that time of 

 a race of men capable of designing and executing such work. 



* ' The Celtic Druids.' 4to. London, 1827. 

 f ' Stonehenge,' &?., 1880. 



