294 



THE TROPICAL AGRICULTURIST. [October i, i8S^. 



less active brother, the 20 £t. wheel, in not having 

 so much of its power absorbed in the raising of 

 speed (a point ignored in theory) and it will be 

 found that the difference in 2>"i''ei' avaihihlc for 

 transmission to machinery has been materially re- 

 duced, while in the case of the 18 versus 

 20 ft. wheels the hair-splitting has become a very 

 fine operation indeed. But to the point ; we have 

 the 20 ft. wheel giving 5 H. P. with a supply of 

 175 cubic feet of water per minute, increase the 

 supply of water by 45 cubic feet (only J of a foot 

 per second) = 220 cubic feet and apply it to the 

 16 ft. wheel, when the same power will be ob- 

 tained theoretically, but somewhat more in practice ; 

 add another J of a feet per second and we get 

 over 6 H. P. and so on ; these figures, I submit, 

 make good my assertion that the diameter of a 

 water-wheel is not the all-important key to power 

 that our teachers would have us believe. 



The common water-wheel is one of our oldest 

 motors, and having been practically cast aside by 

 the modern engineer of the great machinery-using 

 countries, it has escaped the " paring-down " 

 process to which other motors and machines have 

 been subjected, and retains the proportions it re- 

 ceived from the " old school " men, proverbial for 

 erring on the safe side as regards strength of 

 material. Makers of the present day claim improver 

 ments and point to their wheels as models, but 

 when compared with the models of over a quarter 

 of a century ago very little difference will be ob- 

 served either in proportion or design ; in short, 

 their strength is such that I have no hesitation in 

 saying, that the despised 16 and 18 ft. wheels calc- 

 ulated by the orthodox rules for 4 H. P. are capable 

 of carrying water sufficient to develoj) a power far 

 exceeding that of the motor known as a four-horse 

 engine. — Yours truly, D. K. M. 



[We are, personally, much indebted to this writer 

 for his encouraging statement as to the power to 

 which 16 ft. water-wheels can be worked. What 

 we were told by experts was, that if we attempted to 

 turn an Excelsior roller by means of such a wheel 

 the resistance would tear the wheel to pieces. We 

 mean, however, to try the experiment. — Ed.] 



SULPHUEIC ACID. 



De.ui Sir, — Since you were kind enough to turn 

 my platinum into iron-pjaites, I have been favoured 

 with the loan of a pamphlet on the subject of 

 the local manufacture of sulphuric acid, by the 

 late Mr. O'Halloran, so long ago as 1874, with 

 extracts largely from your own columns. 



The study of this has proved to be most inter- 

 esting, and fully answers the question " How is 

 sulphuric acid manufactured '? " When I asked that 

 question, I had it in my mind only as a sub- 

 sidiary process and aid to the local manufacture 

 of quinine ; but this pamphlet shows that that 

 would only be one of a very great many import- 

 ant uses to which this acid is put in agriculture 

 and various manufactures. 



But the subject, as set forth by the late Mr.^i 

 O'Halloran. is a little surprising. After proving 

 to the planters the immense importance to them 

 of an inexhaustible supply of cheap sulphuric 

 acid, he ottered to commence to manufacture it 

 in Colombo, and to fell it at £14 a ton (against 

 the limited supply only that it was possible to 

 import at .tH7 6s 8d per ton) if only orders should 

 bo guaranteed to him of 500 tons ! equal, as he 

 put it, to only 7d an acre for the coffee then under 

 cultivation ! 



Looking back now, it is amazing that this en- 

 couragement was not given to him, for, had it 

 been, who shall say tbiit much, vey much, of 



the coffee now gone out would not still be in ex- 

 istence and paying well ? With an abundant and 

 cheap supply of sulphate of soda, and of dilute 

 sulphuric acid, all these years, the leaf fungus 

 itself might have succumbed ! But surely what 

 was possible then is possible now ? And with the 

 now added demand for sulphuric acid for the 

 manufacture of quinine, with so much tea planted 

 in patana soils, and with a possible supply of 

 iron pyi'ites in the country, the manufacture of 

 this acid ought to be the best i^aying speculation 

 of the day in Ceylon. PLATINUM. 



[In the case of Mr. O'HaUoran's proposed com- 

 pany, "the senior editor" for once, and in view 

 of the public benefit likely to result, broke through 

 the editorial rule against becoming connected with 

 any local Company, helping Mr. O'Halloran to all 

 available information. A\ e received a rather severe 

 lesson to adhere to our rule. Makers and im- 

 porters of manures were all antagonistic, and the 

 de sign collapsed. — Ed.] 



WATER-WHEELS. 



SiE, — Fred. J. Eramwell, in his address to the 

 Institution of Civil Engineers, makes the following 

 statement : — " I will merely call your attention to the 

 improvement in water-wheels in France, an im- 

 provement by which it is asserted that as much 

 as 85 per cent of all the energy residing in a low 

 fall of water has been converted into power, a re- 

 sult due to the decreasing of the speed of the peri- 

 phery of the wheel, and to the making of the 

 buckets very narrow and great depths. 

 In turbines, also, there has been considerable 

 development in these twenty-two years, and they 

 now take their place as very efficient motors, poss- 

 essing many advantages, where, on the one hand, 

 a very high fall of water has to be utilized, or 

 where, in the case of a low fall, great differences 

 in the working head and in the level of the tail 

 water, have to be provided for." 0. E. 



Deak Sir, — It is not surprising that your cor- 

 pesondent " D. K. M." should have such " feeble 

 hold" of the object he writes on — water-wheels : 

 but it is a little, that he has the temerity to 

 criticize Mr. C. S. Armstrong's remarks on tlie 

 same. The man who can make such teas as Mr. 

 Armstrong does must have spent much time 

 and care in finding out how and tin' reason irliy, 

 and it is not surprising that he should have a cor- 

 rect idea about water-wheels as well.* 



The laws which govern the motion and power 

 of a water-wheel were found out long ago by 

 Newton and others, are quite fixed beyond dispute, 

 and have only to be understood to be applied. 

 If " D. K. M." would consult some elementary work 

 on the laws of matter and motion &c., he would 

 find that Mr. Armstrong is right, and that ho 

 ("U.K. M.") has, probably with the best intentions, 

 prematurely rushed into print — with crude ideas. 

 Oh ye teachers ! Beware ! 



Come to the rescue, you, I had almost gaid 

 thou, of the great " Old Bag" sitting there, sur- 

 rounded with cart-loads of books of reference, 

 and a head on your shoulders, like to long for 

 more ! What is wanted is a chapter on water- 

 pon-er in the new Directory, or if more convenient 

 in pamijhlet form. Then every jjlanter could have 

 a' copy, and, after paying for it, be happy for 

 ever, at least on that one thing. Such a pub- 

 lication at this time would save voluminous cor- 



* AVe have great respect for Mr. Aiinstrong's opin- 

 ions, aud yet we have ventured to differ from him as to 

 the power of water-wheela. — JSd, 



i 



