June 9, 1892] 



NATURE 



27 



More remarkable, perhaps, than the position of these circles 

 are their distances from each other, which, on the level map, 

 are almost exactly as 3, 7^, 2, and 8, for the sides of the irregular 

 four-sided figure, of which four of the circles form the corners, 

 while the diagonals are of the same length within a hundred feet, 

 the differences being much less than the I per cent, which Mr. 

 Flinders Petrie has found to be the average error of ancient 

 British and even Assyrian workmanship. The builders of these 



that the distance.^, as shown by the map, are merely the result of 

 accident. 



]f, however, the 25 'i inch cubit were the unit of measurement 

 for the distances between the circles, it ought to appear in the 

 measurements of the circles themselves — and it does ; for the 

 diameter of the Trippet Stones Circle is exactly fifty of such 

 cubits, and the diameters of the Fernacre and Stripple Stones 

 Circles are (as nearly as I can judge in their ruinous condition) 

 seventy of such cubits. 



The Egyptians appear to have constructed separate buildings 

 for the observation of the sun and of the stars, but if the circle 

 builders used the same circles for both purposes, placing them 

 so that when standing in them they could see the sunrise over a 

 fixed point on one hill, and a certain star rise over a fixed point 

 on another hill in another direction, their system was much 

 more economical, though perhaps less exact than that of the 

 more civilized Egyptians. A. L. Lewis. 



The Height of the Nacreous Cloud of January 30. 



The cloud referred to by Mr. T. W. Backhouse, in your issue 

 of February 18 (p. 365), attracted universal attention over East- 

 ern Yorkshire and even in Lincolnshire, so that numerous letters 

 were sent to the Leeds Mercury, Yorkshire Post, &c. 



Its general appearance in these parts is being dealt with by 

 Mr. H. Bendelack Heweison, of Leeds. I will therefore merely 

 state that the intensity of the fringes surpassed anything in my 

 previous experience. Even those observed in 1884-85, in con- 

 nection with the Krakatab glows, did not approach it in this 

 respect. 



Here, as it happened, Venus lay just upon its lower edge. 

 As this was fairly horizontal, save for a break not far from the 

 middle, I was very pleased to get from Mr. C. J. Evans, Ack- 

 worth, near Pontefract, a second observation. In response to 

 further appeals, observations, of varying accuracy, from the 

 places in the subjoined table, were available for calculating the 

 height. 



Leeds (Prof. A, Lupton saw the cloud "nearly overhead," 

 "if not, a little S.S.W.," "within 20^ of the vertical"), Ack- 

 worth, and York enable us to determine the direction and posi- 

 tion of the central part of the lower edge of the cloud as seen 

 from the north and east. They give a point just above Mirfield 

 Junction, 9 miles S.S.W. from Leeds, 32 miles S. W. from York 

 and 13^ miles W. of Ackworth. The Driffield direction passes 

 the same spot. The only other record, Market Rasen, is very 

 divergent, the observer there putting the centre point south of 

 west, whereas Mirfield is north of west. 



The altitude of this point was capable of closer determination, 

 thanks to references to Venus and Jupiter. The results of careful 

 reductions are given in degrees in the following table, accom- 

 panied by the corresponding heights in miles, and distances and 

 directions from Mirfield. 



circles may be supposed to have aimed in their measurements at 

 even numbers of some unit, and the unit which gives the best 

 results appears to be a Royal Persian or Egyptian cubit of 25*1 j 

 inches (not at all the unit one would expect). The actual 

 measurements, as nearly as I can get them from the 6-inch 

 Ordnance map, are : — 



Feet. 



Stannon Circle to Fernacre Circle 

 Fernacre Circle to Stripple Stones 



(Practically 7500 cubits) 

 Stripple Stones to Trippet Stones 



(Practically 2000 cubits) 

 Trippet Stones to Stannon Circle ... 16575 

 (Probably meant for 8000 cubits) 



Diagonals. 

 Fernacre Circle to Trippet S'ones 



Cubits of 

 251 inches. 

 6275 = 3000 

 15730 = 7520 



4180 = I99S'4 



7924 



Stannon Circle to Stripple Stones 

 (Perhaps meant for 8125 cubits) 



16950 

 16^50 



8103 

 8055 



It must not be forgotten that these mea-;urements are taken 

 from the level map, while the ground between the circles is very 

 irregular, but it seems more probable that the builders of these 

 circles made allowance for the irregularities of the ground than 



NO. I 180, VOL. 46] 



The ailopted height from the above eight records is 14 miles, 

 or 75,000 feet. 



'1 he Leeds rtcord gives 25 miles, but Prof. Lupton wrote 

 only from memory, in response to inquiry after some interval. 

 It may, however, indicate that the souih-vest edge of the 

 cloud was more nearly above Leeds. By shifting it 4 miles 

 in that direction the Leeds height becomes 16 miles, and that 

 for Ackworih \\\ miles, Tadcaster 12*, York 12, and the rest, 

 except Market Kasen (unchanged), become half a mile less. 

 The mean result, taken as before, but now including Leeds, is 

 13 '6 miles, or substantially the same, 



1 As the records at these stations appeared to be much the more trustworthy, 

 double weight is given them in the rcductd value. In the Ackworth value, 

 four times the weight is assigned 10 the 40' as to the 45", the latter, on in- 

 quiry, being stated to be less probable. 



