Sept. 19, 1884.] 



• KNOWLEDGE ♦ 



245 



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TEA AND COFFEE. 

 [1397] — I quite corroborate the statements of Mr. Williams 

 with regard to the imbibition of tea and coffee, and the manner in 

 which they affect the constitution. For years I was accustomed to 

 drink freely of both ; it had become, of course, quite a habit, and 

 one not easy to shake off. Three months ago I left off drinking 

 both, and, although I missed them at first (suffering from frequent 

 headaches and irritability), I now, and for the last two months or 

 more, hare never felt better in my life or more fit for mental 

 labour. I always drink hot milk in place of these unnecessary 

 stimulants, and I know of no better restorative after any kind of 

 work. The boiling of the milk destroys any germs that might exist 

 in it. Tea or coffee after dinner in the evening always had the 

 effect of keeping me awake at night, thus showing the powerful 

 way in which they act on the systems of some people. I believe 

 stimulants of all kinds to be quite unnecessary, excepting in certain 

 cases of illness. As for mustard, cayenne pepper, and such-like 

 condiments, I do not think it advisable to let the coats of one's 

 stomach be subjected to sensations that one's tongue can scarcely 

 endure. C. Cakus- Wilson. 



FIGUKE PUZZLE. 



[1398] — I have met with the following figure puzzle ; can any of 

 your readers solve the same ? 



Let A B C D E F equal the number. 



Then B C D E F A will be thi-ee times the original number ; 

 CDEFAB „ double 

 DEFABC ,, sis times ,, ,, 



E F A B C D „ four „ „ „ 



FABCDE „ five „ „ 



E. SiDDER. 



FALSE PERSPECTIVE. 



[1399] — If I do not trespass too much on your space and patience, 

 I shall be glad if yon will kindly insert the following in answer to 

 your correspondent, "J. H. D." (Xo. 13S(3.) 



If an object at A appears smaller than a similar one of equal size 

 at B, because it is further off, so Ukewise, and for the same reason, 

 will it appear smaller than B when it is moved to h. 



The painter must depict things as they appear to the eye; it is 

 for the sculptor to represent them as they exist in nature. 



E. Jones. 



[1400] — I suppose that "E. E." and "J. H. D.'s" explanations 

 will convince R. Jones that the accepted method of drawing 

 horizontal lines parallel to the picture plane is correct. Many 

 beginners in perspective and persons unacquainted with the subject 

 entertain his idea. The example which R. Jones gives in his letter, 

 No. 1384, is one that is sometimes called parallel perspective, 

 which, like all perspective, supposes the eye to be fixed and directed 

 at right angles to the picture plane, the picture being limited to 

 the base of a cone, whose apex at the spectator's eye is an angle of 

 60". If he will look at the street under these conditions, he wiU 

 observe no perceptible trending away of the horizontal lines, 

 parallel to the picture plane. On his principle, the vertical lines 

 would also seem to vanish, skywards or earthwards, according as 

 his position was low or high. He may rest assured that if either 



the horizontal or vertical lines have vanishing-points, they are at 

 an infinite distance, and that there is no more occasion to represent 

 any inclination than there is to consider the rays from the fixed 

 stars other than parallel. As soon as he turns his eye up or down 

 the street, the picture plane, which is at right angles to the central 

 visual ray, moves round too, the horizontal lines are no longer 

 parallel to it, and the street is then in angular perspective, and the 

 top and bottom edges trend away to their respective vanishing- 

 points in the horizontal Une. Eye-Witness. 



[1401] — In case no one else has replied to Mr. T. E. Jones's 

 letter in your number of August 15, I would point out that his 

 reasoning is detective. According to his argument the projection 

 of the Une of posts, if produced both ways, would converge both to 

 left and right, the line of tops, thirdly, forming an angle at the 

 centre, and we should have a case of a projection of a straight line 

 on a plane consisting of two straight lines meeting at an angle, 

 which is impossible. The real fact is that, in the case supposed, 

 where the axis of sight is at right angles to the plane of the line of 

 posts, the latter all actually appear to the eye to be of the same 

 length equidistant. This follows as a geometrical consequence of 

 the plane of projection being parallel to the plane of the object. 

 Anyone can verify this by examining a photograph of a building in 

 which the camera has been pointed square to its front, as it were. 

 It is only when the camera (or the eye) is turned obliquely to the 

 line of posts that their distances diminish in proportion, and their 

 parallel lines converge. Musafik. 



Cainada, 29th August. 



CLEMENTS' WEATHER CYCLE. 

 [1402] — As I found the node-cycle of the moon did not quite 

 satisfactorily account for the recurrence of rainfall at London, I 

 combined the apse-cycle with it, obtaining a 10-3 years' cycle by 

 finding the product of one-fourth of each of these cycles, the moon's 

 orbit and the nodes and apses of 186 and SSo years respectively 

 being divided into four well-marked portions. And as this com- 

 bination-cycle somewhat imperfectly accounted for the London 

 rainfall, I combined with it the London tide-cycle, which I had just 

 accidentally discovered, thereby changing the 10'3 into a 2035 

 years' cycle, by mtUtiplying by 1'98 the fourth of 7'93 years, the 

 time occupied by the tidal revolution. This 20i years' cycle 

 accounts for the London rainfall so satisfactorily that there is little 

 or nothing further to be desired. In fact, the nodal and apsal 

 cycles account for the general terrestrial rainfall, and the local 

 tidal cycle satisfactorily accounts for the local variations. As the 

 successive position of these cycles can be determined with absolute 

 precision for the future as well as the past, the rainfall at London 

 and elsewhere can be predicted with much certainty for any 

 number of years in advance. From this cycle we may obtain a 

 multiple cycle of 61 years, and the intervening cycles of 30-5, 

 40-7, and 50-9 years, with a sub-cycle of 10-175, or nearly 

 10-2 years. From the 20i years' cycle, it wiU be observed 

 that the wet and dry years, together with those of an average 

 rainfall occur in the" same part of the cycle respectively 

 with great regularity. For instance, lOJ, 20i, 30i, 40f , 50J, 61, 

 and 71 J respectivelv," added to the wet year 1821, give the wet 

 years 1831, 1841, 1852, 1S62, 1872, 1SS2, and 1892, and, deducting 

 the same figures successively from the present drv year, 1884, we 

 obtain the dry years 1874, 1864, 1854, 1844, 1834, 1823, and 1813. 

 with a similar result any year may be taken and the additions or 

 deductions made. Coming to the near future, it may be seen from 

 the diagram that the years 1894 and 1895 will correspond with 

 1873 and 1874, and that the years between will be dry or mean 

 except 1885, 1889, and 1892. In fact, the weather in Engla.nd 

 repeats itself every 61 years, and I have verified this repetition 

 down to the commencement of the Christian era. 



Hugh Clements. 



[I insert Mr. Clements's letter without possessing the slightest 

 faith in his system. But ars probat artincem, " the proof of the 

 pudding is in the eating." He makes definite vaticinations of rain- 

 fall and drought, and it only remains to be seen whether they are 

 fulfilled or not.— Ed.] 



AERIAL LOCOMOTION. 

 [1403] — Tour recent articles treating on air-navigation I have 

 read with great interest. Still, I think you have omitted the most 

 important name in the list of those credited with aiding the pro- 

 blem of flight to a solution. I refer to Charles Darwin, and 

 instance his observations on the condors of South America given in 

 his " Naturalist's Voyage Round the World," written nearly half a 

 centurv ago. 



