138 



• KNOWLEDGE • 



[Mahch 2, 1883. 



DKSERT OV ATACAMA. 



[7'Uj] — I have lately been convcreinK witli a Keiitleman vvlio was 

 at Olio time vico-consul on tho West coast of South America, and 

 wlio had inado au extensive and careful survey of tho Desert of 

 Atacama, in Chili. I am anxious to loam what were tho causes 

 which produced that desert ; and, not tiuding any .account of them 

 in any hooks to which I have access, I woulil like if you, or any of 

 your Kcolofcicul friends, would favour me with an explanation. 



What this >rentlomau has told mo is, that for more than a 

 hundred miles south of Pisco, and again for seventy miles north of 

 Canote, there is absolutely no vegetation whatever, but that num- 

 berless water-courses, now quite dry, can bu clearly traced running 

 up into tho mountains, some of them, in their lower ranges, 1,500 

 to 2,000 feet in depth, and one of them two miles in width ; and 

 that at their mouths, towards the sea, there are great accumulations 

 of boulders, gravel, and sand, sometimes running far out below the 

 sea, and showing a depth of cliSf, where they have been cut into 

 by the sea, of .'!U0 feet or so. 



Along the banks of these water-courses there are found millions 

 of human bodies interred in the sand, with their implements for 

 hunting and fishing, where now there is not a blade of grass or drop 

 of water within immense distances. 



On ascending the mountains to the east of this desert— the Sierra 

 of San Andreas — near Islay, he conld trace these water-com-.ies to 

 great heights— gradually diminishing, of course, in depth, and 

 bifurcating into small tributary depressions as he ascended. In 

 one place he came upon what appeared to be the bed of an ancient 

 lake, now (luite dry, at a height, as his Indian guide assured him, of 

 14,000 feet {?} above the level of the sea. 



Along the sides of the deepest ra\nne3 he found terraces — terrace 

 above terrace — rising sometimes as high as 1,000 feet above the 

 bottom of the ravine, and which he believed were the remains of 

 aqueducts for bringing the water from the higher to the lower 

 levels for the purpose of irrigation. 



From all these facts he concludes that this desert, in at least the 

 mouths of its great ravines, must at one time have been highly 

 cultivated and populous ; and what he and I would like to know is, 

 ■what brought about so great a change ? Can it have been that this 

 lower flank of the Cordilleras is much older than the higher ranees 

 to the east, and that therefore the rain-clouds which now discharge 

 themselves upon the higher range, had at one time discharged upon 

 the lower ? Senex. 



[It is not quite clear what connection exists between the desert 

 of Atacama, in Chili, and the desert region around Canete, Pisco, 

 and Islay, in Pern. — R. P.] 



LETTEKS RECEIVED.— CONTENTS NOTED. 



F. R.— J. N. D.— Faciebat— T. L.— E. H. M.— J. B. Canu— F. C. 

 — Tekel — J. E. S. — J. Pocock— Jane Johnson — W. — F. W. Ashley 

 — W.— An Admirer of a Small Waist— A. J. Maas — A Native of 

 Wales— E. Eggenschinler— R. B.— T. C. S.— H. C. Wilmot— L. P. 

 Whitmore— Acoustics- C. M.— W. B. K.— R..G.— G. S. Coombe— 

 W. G. Rolfe— C. W. Bourne— Undergraduate— H. C. Dent— Star- 

 gazer— Constant Subscriber— G. F.— S. E. Clarke— E. J. L.— More 

 Light— J. O. K.— R. N.— J. W.— A. C— Arthur— W. M.— P R — 

 Indian— C. W. B.— J. S.— S. S.— A. W. C— H. J. S.— G. S. G.— 

 A. S.— W. Moor — W. Suuter — J. G.— C. Reeves— H. W. J[.— 

 Zamiel— W^ H. A.— Another Observer— W. A. F. 



Mr. C. F. Brush, the inventor of the dynamo and arc lamp 

 named after him, has taken out a patent for a system of storing 

 electrical energy. It occupies 46 pages of print, and wo hope t'o 

 be able to refer to it more fully at au early date. 



Mr. W. H. Pkkece, F.R.S., addressing the Institute of Civil 

 Engineers on the 15th ult., said that there are at present in use in 

 the postal telegraph system, 87,231 Daniell cells, 56,-l20 LiSclancho 

 colls, and 21,810 bichromate (Fuller) cells, lie is also credited with 

 the somewhat remarkable statement that, " Thanks to such expe- 

 ditions as that of II.M.S. ChuUengor, tho floor of the ocean is 

 becoming more familiar than the surface of many continents." 



It is very interesting to note that Messr.s. Chubb & Sons turn out 

 yearly about 1,000 safes, strong rooms, and iron doors, and 40 000 

 locks. Over 1,000,000 of the patent detector looks have been 

 made. There are 200 men employed, all on piecework, and the 

 average service of each man is said to be seventeen years. This 

 indicates a satisfactory state of things all round. One of the latest 

 productions is a safe weighing nearly twenty tons, made for the 

 Government of the Argentine Republic. It is estimated to be lar'-e 

 enough for the storage in bags of Jt 18,000,000 in gold. ° 



^ur iHatOftnatical Column* 



A MATHEMATICAL LETTER (A,). 



TURNING over some of tho earlier pages of Knowledge, 1 came 

 upon your article on tho interesting curve called " the Witch 

 of Agnesi " ; and this brought to my mind a reminiscence of old 

 Cambridge days, followed by other reminiscences which, if you wiB 

 allow me a jiage in your periodical, may be amnsing to your readers. 

 You remember our Sadleirian Lecturer in '59 ? De vivits nil nin 

 boimm. I hope he will forgive the confession, but I know the' 

 culprit who sent him the valentine. It was very harmless : simply 

 this, "r = « (1 — cos S), from your loving ac i/" = 4a' (2 a — a) ." li- 

 being St. Valentine's d.ay, I had the satisfaction of seeing him trace 

 the former of these (the Cardioide) upon receiving the letter in HalL 

 Tho latter, however (the Witch of Agnesi) , was not recognised nntQ 

 the pastry made its ajjpearance, when a loud guffaw proclaimed thait 

 enlightenment had come. How he used to trouble us with his pet 

 subject, the Golden Number! There was nothing ho was not capable 

 of turning into mathematics. " Magistrates conniving at certain 

 periodical religious riots " (so ran one of his Little-go questions in 

 allusion to the disturbances taking place at St.Geurge's-in-the-East), 

 " fined the offenders inversely in proportion to the damage done," Ac 

 But there never lived a sounder mathematician. It was he whe 

 first really brought home to the Little-go candidates the fact that 

 division embraces the dividing of concrete numbers by concrete 

 numbers — a fact which, appearing in one of Mr. Gladstone's speeches, 

 was challenged by a leading Member of the House of Commons, and 

 was settled by an appeal to Mr. Fawcett, as a Wrangler — and the 

 form of question by which the Little-go mind was enlightened waa 

 as follows : — Find the value of 



9a 4r 3d 16h 



And then what devils he used to turn out in May ! I ask your 

 readers' forbearance until I have explained, as the following in- 

 cident reminds me that my language may be misunderstood. A couple 

 of Johnians in a railway carriage on their way " down " were dis- 

 cussing their recent experiences. " Did you get out the second 

 devil ? " asked one. " No," replied his companion ; " I worked atit 

 for au hour-and-a-half, and could do nothing with it ; but I got outj 

 the last two." The horror-struck look of an old lady in the same 

 comjjartment, who changed her carriage at the fii'St opportunity, 

 was quite lost upon the students. Be it explained, then, that in 

 former days a paper of seven stiff equations was set at the May ex- 

 amination at St. John's, which were universally referred to as " the 

 seven de\-ils " — so universally, that I believe the phrase passed^ 

 current among the examiners themselves. Would your readers likflj 

 to see a sample ? Here is one, — 



1 (x + 1) (a^-3) _^^l (x + 3) (x-5) _2 (»-!-5) (j;-7) ^92* t 

 5 ■ (a; -1-2) (a; -4) 9 {x + 4) {x-&) is' {x + 6) (x-S) 585 ♦! 



The last three equations, if I remember aright, were problems, anft 

 were called black, as opposed to blue devils. [They were so. — Ed.] 

 Speaking about problems, I remember that one of our lecturer^ 

 gave us some instruction on the subject of betting, which has also bs 

 discussed in your pages. The problem given was in this form : " Th 

 odds against a horse (A) winning are a to 1 ; against B winnu 

 & to 1 ; against C winning, c to 1, and so on. Prove that in order \ 

 win for certainty P pounds, a man must back A to the amount of | 



P-5-(a-t-l) i 1-J_-_L__1_, &c.| 

 ^ ' I a + 1 h + 1 c-i-1 3 



and B, c, &o., for like amounts, putting 6, e, &c., for a in the nu"! 

 symmetrical part of the above expression." 



The gentleman from whom I received the above was so completely I 

 saturated with mathematics that he described three young ladies in I 

 a family, who strongly resembled one another, as Miss Richardson,! 

 Miss Richardson dash. Miss Richardson double dash : and npoml 

 being questioned one day as to the cause of liis apparent ill-health, I 

 said, that " he had passed a dreadful night : ho had dreamed tha' 

 he was under the sign of the square root and couldn't be extraotedi- 1 

 I conclude with two ancient questions for your readers. 



1. If a man be placed on a perfectly smooth horizontal table, hovl 

 can he get off ? 



2. Explain how the juice collects in the cup placed inside >| 

 fruit tart — (a) when tho tart is air-tight. ((3) when it is not. 



N.B. — The case of the tart being more than 32 feet high may be| 

 neglected. A Wrangler. 



* The devil may be expelled from this particular abode by re- 

 garding (' — 2.C as the unknown, and noticing that 



5 9 11! 585 K- P- 



