October i, 1885.] THE TROPICAL AGRICULTURIST. 



293 



COFFEE VERSUS TEA. 



LauKilale, Liiiflula, 4tli Sept. 1885. 



Siu, — I send you an extract from a liome 

 letter : — 



" You ask it we drink Ceylon tea ? and the 

 answer is, the grocers do not care about it, they 

 say it cannot be depended upon, it varies so much; 

 and if so, why cultivate it ? Then again, doctors 

 are setting their faces against tea : two doctors 

 advised me not to drink it at all. So we only use 

 it for afternoons, and even then at many houses 

 coii'ee is ofi'ered at afternoon tea parties, so many 

 people are not allowed to touch tea. In the 

 hospitals now coffee is - given as a stimulant 

 instead of brandy, and everywhere it is being pre- 

 ferred ; so why turn your coffee into tea plant- 

 ations ?" 



You may make any use you wish of the above 

 extract. 



Weather still very dry, not at all seasonable : we 

 want some rain. — Yours faithfuUv, 



AKTHUR HEELIS. 



[The reply to which is that the consumption 

 of coffee in Britain has decreased, while that of 

 tea has rapidly increased. If coffee trees continued 

 to grow and yield well in Ceylon, no one, of 

 course, would thmk of superseding them by tea 

 bushes ; but, alas ! in a large number of cases 

 there is no choice but to say of coffee : " Why 

 oumbereth it the ground ? " — Ed.] 



THE POWER OF WATEE-WHEELS. 



Colombo, 4th Sept. 1885. 



De.vk Sik, — In reply to " D. K. M." 'sletter in your 

 valuable paper of 3rd instant, the difference in 

 power between a 16 ft. and 20 ft. diameter water- 

 wheel with 480 cubic feet of water per minute 

 passing over them is that the 20 ft. water-wheel 

 will develope 13-7 H. P. while the IG ft. wheel 

 will only give 10-9 H. P. The power of a well- 

 made water-wheel or turbine may be easily calculated 

 by multiplying the cubic feet of water per minute by 

 the height of the fall and dividing by 700 : the 

 quotient will be the horse-power of the wheel. 



In driving a double pulper and crusher about 

 2J H. P. is generally used, and most of the water- 

 wheels on Ceylon estates have been built for work- 

 ing at that power, but they are calculated for 4 H. P. 

 which gives a good margin of safety for the pur- 

 pose they were intended ; if driven above that they 

 are liable to break down, as neither shrouds, axles 

 nor spur-wheels are safe for more. 



Jlr. Armstrong in his jjaper on Tea Machinery 

 is inclined to give his preference to water-wheels 

 instead of turbines, and 1 agree with him that 

 where small power is only wanted with medium falls 

 the water-wheel, has many advantages, but there 

 are few estates in Ceylon that can afford 400 cubic 

 feet of water per minute on falls of 20 ft, (equal 

 to about 11 H. P. ) which is what a medi- 

 um tea estate will require, but many of 

 them with half that quantity of water and double the 

 fall when turbines can bo used with good effect. 



I extr.;ci ihc follov,-iiig irom one of the best 

 publications on water motors that I know of,' which 

 I think will be interesting to many of your readers : — 



"If a ponderous vertical wheel be applied to a 

 verj' high waterfall, its diameter will be so large, 

 and its revolutions so very few, that it mnst be 

 connected with a great deal of auxiliary machinery 

 to impart that rapid motion which is generally 

 required. On the contrary, the turbine being com- 

 paratively so small and its revolutions so numer- 



• Name?— Ed, 



ous i" ,'' given time, its motive power can be ak 

 once transmitted. 



" Moreover, what operates as a disadvantage 

 in the ordinary wheels, contributes to the more 

 efficient working of the turbine ; for the higher 

 the waterfall, the smaller, and consequently the 

 less expensive, the turbine adapted to it ; and also 

 it is applicable on falls of water so high that 

 the ordinary wheel cannot be used. Another great 

 property of the turbine is its constant and 

 uniform motion, which arises from the diffusion 

 of the impelling water over the whole of the 

 circumference at the same instant. This perfect 

 uniformity of motion is a peculiar feature of the 

 turbine. The turbine is capable of working under 

 the back water as long as the surface of the 

 fluid in the reservoir remains the highest, during 

 which time it will jDroduce a moving force pro- 

 portional to the difference between these two levels, 

 without a perceptible diminution of the useful 

 effect, thereby evidencing that it is exempt from 

 the casualties to which the vertical wheel is so 

 often subject. 



"If a turbine be connected to a steam-engine 

 during the dry months while ^^■ater is scarce, it 

 can be made to transmit the highest obtainable 

 power from the quantity of water by which it 

 may be supplied, and it can be made so large 

 as to drive all the works in the wet months. Saving 

 the expense of fuel, economising that liquid that 

 commonly runs to waste, and giving sufficient time 

 for any repairs that might be required on the 

 steam-engine, clearly showing the great advantages 

 of the turbine over the vertical wheel, for it could not 

 be made so large as to receive the extra water in 

 wet weather, without lessening the effective power 

 of the smaller quantities in dry weather. 



" It is a fact of vast importance that turbines on 

 the improved principle of construction, supersede 

 in America, France,, and many other part of the 

 Continent every other description of water-wheels, 

 and after long experience of their superior work- 

 ing power in impelling machinery, however ponder- 

 ous and complex, have been stamped with the 

 approbation of the most eminent mill-owners and 

 manufactures. And I am firmly convinced that their 

 general introductionis now a mere question of time." 



I trust the above may be of service to some 

 who may be seeking imformation about water-power, 

 and remain, yours truly, WALTER LAMONT. 



Colombo, 7th Sept. 1886. 

 Dear Sir, — I am pleased to see in your issue 

 of Saturday evening that Mr. Lamont, an ac- 

 knowledged authority, has stepped to the front 

 with an answer to my simple question on the 

 power of w'ater-wheela. Those who liave investig- 

 ated the subject are aware that the various works 

 treating on water power as applied to the ordinary 

 I vertical wheel, although at one approximately, 

 i yet do not all agree in detail, important facts 

 being pointed out which are worthy of consider- 

 ation when estimating the effective power of 

 small wheels, such as are employed in Ceylon ; 

 as, however, the columns of a newspaper are not 

 the place to enter into calculation, I accept Mr. 

 Lamont's theoretical formula, and apply it to the 

 case of the numerous water-wheels in Ceylon 

 (which he says are mostly calculated for 4 H. P.) 

 as follows : — 



175 cub. ft. of water per minute applied to a 

 20 ft. wheel give exactly 5 H. P., while the same 

 quantity of water applied to a 16 ft. wheel gives 

 a result of exactly 4 H. P., but credit the latter 

 irith the advantage it possesses over its bigger but 



