380 



SCIENCE 



[N. S. Vol. XXXIV. No. 873 



group and the massive Eedwall become grad- 

 ually thicker to the northward and westward, 

 and the inner canyon narrows as these strata 

 become more and more effective in defending 

 the retreat of the wall. 



In the Kanab division, the Supai formation 

 of the Aubrey group consists of weak red 

 shales in the upper portion and resistant 

 sandstones below. The shales waste back 

 from the summit of the sandstones, leaving 

 the Esplanade platform. In the western part 

 of the quadrangle, where the Esplanade is 

 fully developed, the thickness of the Supai 

 shales is 550 feet; while that of the overlying 

 massive white Coconino sandstone, which de- 

 fends the retreat of the outer wall, is only 250 

 feet. Eastward from Havasupai Point, in the 

 Kaibab division, the thickness of the Supai 

 shale has decreased to 300 feet (becoming still 

 thinner in the Bright Angel quadrangle to 

 the eastward) ; while that of the Coconino 

 sandstone has increased to 400 feet; the 

 Esplanade fades to a narrow ledge in this 

 part of the canyon. L. F. Noble 



Valyermo, California, 

 July 27, 1911 



DRAUGHTS AND COLDS 



To THE Editor of Science: In reading the 

 interesting and instructive communication 

 by Mr. M. Mott-Smith in the August 4 num- 

 ber of Science, I was impressed by the closing 

 paragraph, which follows : 



Though the above explanations are only a re- 

 hash of well-known principles, I hope they may 

 be of some use. In return I wish some one would 

 explain to me just what is the danger of the open 

 window. Why is a little sneaking draught in the 

 house a source of colds and grippe, while a high 

 wind out of doors a pleasure and a benefit? This 

 is a problem that has long puzzled me, but perhaps 

 it is a foolish question. 



This problem has doubtless puzzled a great 

 many besides Mr. Mott-Smith, and is perhaps 

 " a foolish question " ; but why it should be a 

 foolish question seems also a puzzle to a lay- 

 man. The problem appears to involve the 

 question, what is the pathology of a "bad 

 cold " ? The writer has propounded that 



question to several intelligent physicians, and 

 its " foolishness " is attested by failure to 

 elicit any attempt at a lucid reply. 



The writer has been compelled to construct 

 for himself what engineers would call a 

 " working hypothesis " to cover this problem, 

 and has even ventured to apply a quasi scien- 

 tific name to fit the case, which is offered as a 

 reply to Mr. Mott-Smith for what it may be 

 worth, or otherwise, with all due diffidence and 

 a proper sense of his temerity in trenching 

 upon hallowed ground. 



The answer thus boldly formulated as to 

 the proximate cause of a " bad cold " is, a dis- 

 turhance of the thenno-neural equilibrium 

 of the surface of the body. 



It is a matter of common experience that if 

 a portion of the body, the head and neck, for 

 instance, is exposed to a strong breeze while 

 the remainder of the body is of normal or 

 supernormal temperature, bad cold, grippe, 

 etc., are pretty sure to result, while the " high 

 wind out of doors," which envelops the 

 whole body, has no such effect. One sitting 

 in a country ofiice on a very cold day, his feet 

 thrust under a desk and his back to a glowing 

 grate, shall after a while fall to sneezing, and 

 if he is wise he will get up and stir around in 

 order to restore this disturbed equilibrium in 

 the temperatiire of the cutaneous nerves. 



In this connection it may be said that the 

 writer has found what is to him a completely 

 satisfactory solution of the weighty question, 

 how to deal with the long and oppressive sum- 

 mer heat in the southern states, to wit, the 

 electric fan. 



Nearly all persons are afraid to allow a fan 

 to blow upon them while asleep; and indeed 

 if the body is partially exposed to the action 

 of the fan it is a dangerous practise. On the 

 other hand it is the writer's constant practise 

 to have a 16-inch fan blowing upon him all 

 night in hot weather. When the temperature 

 is very high the fan is run at top speed, and 

 is graduated down for lower temperatures. 



The point to be made is, that the fan is so 

 located that it is in line with the sleeper's 

 body, taking him from his feet to his head, 

 and thus enveloping his entire body in the 



