December 29, 192 1] 



NATURE 



587 



tigation and interpretation by modern colloid chemis- 

 try. Non-aqueous colloid systems present as yet an 

 almost entirely new field. 



Prof. Bancroft has presented in very readable form 

 stimulating problems which should serve to emphasise 

 the growing necessity few the research weaker in all 



branches of chemistry to keep in close touch with the 

 future developments of a branch of his science under- 

 lying all industrial chemistry, but which, unfor- 

 tunately, is not yet sufficiently recognised in the curri- 

 cula of universities and other institutions possessing 

 honours schools of ch«mistrv. 



Orientation in Egypt.* 

 By Col. H. G. Lyons. F.R.S. 



MR. RICHARDS 'S short note of eleven pages, 

 which has been published by the Survey of 

 Egypt, deals with observations which were made in 

 1913 and 1914 to determine the azimuth of the axis 

 of Karnak temple. In i8go Sir Norman Lockyer 

 took some preliminary observations, which suggested 

 to him that the temple at the time of its foundation 

 had been definitely oriented to the sun at sunset at 

 the summer solstice, a conclusion which others made 

 by Mr. Wakefield in 1891, and later by Mr. Howard 

 Payn (Nature, October 19, 191 1) appeared to con- 

 firm. 



On all these occasions, however, the line of the 

 temple axis w as much obstructed by fallen blocks of 

 masonr)-, and not until 1913 was the clearing so 

 far advanced that satisfactory observations could be 

 made. The results then obtained dilTered considerably 

 from the earlier ones. As a control the temple axis 

 was carefully surveyed in 19 14, and a new determina- 

 tion of the azimuth was then carried out, which fully 

 confirmed that of the year before, namely, 26° 54' o" 

 north of west. The declination of the sun for it to 

 shine down the temple axis must, consequently, be 

 25° 9' 55", instead of 24° 18' o", which the earlier ob- 

 servations had indicated, and the date of foundation 

 deduced therefrom, instead of being 3700 B.C., would 

 be carried back to a time far anterior to the earliest 

 estimate of any Egyptian civilisation. Karnak temple 

 cannot, therefore, be a solar temple having its axis 

 directed to sunset at the summer solstice. 



1 ■' Note on the Age of the Great Temple of Ammon at Karnak as 

 determined by the Orientation oi its Axis." Hv V. S. Richards. 

 (Cairo Government Press, igii.) 



It had seemed that much support was given to the 

 hypothesis of orientation by inscriptions which defi- 

 nitely describe the foundation ceremony as including 

 the stretching of the measuring cord and the align- 

 ment of a peg on a celestial body. But our knowledge 

 of the foundation ceremonial is still incomplete, and 

 it is doubtful if it described a practice which was 

 carefully and accuratelv carried out at the founding 

 of each new temple ; more probably it was/ a very 

 earl}- rite, which had become purely ceremonial by 

 the time when masonr}' temples were erected, and 

 when other considerations often influenced the laying 

 out of a site. 



At Karnak the axis of the sanctuary, of which the 

 azimuth was determined, was 35-5 metres long, but 

 on account of weathering the centres of various door- 

 ways cannot be determined within a centimetre, and 

 an error of 1' in the azimuth, which may be intro- 

 duced bv this, would alter the date by some 190 

 years. 



Luxor temple has been quoted as a case of a temple 

 in which successive additions we're laid out with 

 slightiv different azimuths of their axes to compen- 

 sate for the changing amplitude of the star, which 

 could no longer be seen along the axis of the earlier 

 portion. But Borchardt (Zeitschrijt i'tr aegyptische 

 Sprache, vol. 34, 1896) has indicated conditions on the 

 site which may equally have necessitated the slight 

 displacements of the later additions, apart from any 

 astronomical considerations. It seems, therefore, un- 

 likely that the foundation dates of Egyptian temples 

 can be determined more accurately from astronomical 

 data than bv archaeological methods. 



Experiments on Plague Eradication in India. 



TN "An Experiment in the Eradication of Plague 

 -■■ Infection carried out in the Poona and Adjacent 

 Districts : First Report (for the period 1914-16)," 

 and " Further Experiments in Plague Prevention 

 carried out at Poona : Second Report (for the period 

 1916-18) " (Indian Journal of Medical Research, 

 vol. 8, No. 3, Januar}', 192 1), Major J. C. G. 

 Kunhardt, I. M.S., and Assistant-Surgeon G. D. 

 Chitre give their experiences as to the possibilities of 

 eradicating plague by rat reduction during the non- 

 epidemic season, and suggest improvements in the 

 methods of rat-destruction. 



The basis of the work is the finding of the Plague 

 Research Commission that epidemics of bubonic 

 plague in India may be regarded as entirely dependent 

 on, and perpetuated by, epizootic plague in rats. 

 Hence measures for increasing the immunitv of man 

 by inoculation, or for protecting him from infected 

 fleas by evacuation, flea-destruction, etc., could, by 

 themselves, in no way bring about the eradication of 

 the disease from any area ; and measures for the 

 eradication of plague infection must depend entirelv 

 on the reduction of the rat population. This reduc- 

 tion can be effected indirectiv, either bv limiting the 

 shelter and food-supply of rats, or by ifostering their 



NO. 2722. VOL. 10.8] 



natural enemies; or directly, by their destruction with 

 traps, poison baits, etc. Practical considerations of 

 several kinds, however, convinced the authors that 

 active rat-destruction was the only available 

 measure. 



The method adopted depended on the fact that 

 there is normally-, in every year, a season when 

 plague dies down. .The new epidemic may be started 

 either through the importation of infection from out- 

 side, or through the recrudescence of the disease 

 harboured, though not manifest, in the area itself. 

 In the area selected for experiment^ — the districts of 

 Poona, Ahmednagar, Satara, and Sholapur — the "'off- 

 season " includes April, May and June. 



It has been shown that in the great majority of 

 places infection dies out completely before or during 

 the off-season. It may not do so, however, in a 

 large town or village, or one into which infection was 

 first introduced comparatively late in the plague 

 season, since here a number of rats would still be 

 present at the beginning of the off-season, sufficient, 

 sometimes, to enable a rat-epizootic to smoulder on 

 during the unfavourable period. L'nder the opposite 

 conditions — small town or village, and earlv introduc- 

 tion — the rat population becomes so reduced bv the 



