44 
THE TROPICAL AGRICULTURIST. 
[July a, 1894. 
It would ba beyonl the scope of a letter to a non- 
t9ohnioal papor to attempt to enter into an expla- 
nation of what eleotrioity is, but it may be 
worth stating, paradoxioal aa it may seem, 
that the mysterious something we oall eleotrioity 
performs its duty to the laws of nature, not so much 
in the conducting wire aa in the "ether" round it. 
Without this assumption all the marvellous 
phenomena of " induction " would be quite in- 
explicable. 
As far S3 the tea planter is concerned eleotricity 
yields a convenient means of transforming the energy 
of falling water (to speak loo3ely) in a distant 
waterfall into mechanical energy in the tea factory. 
Now water power, pure and simple, in many 
parts of Ceylon costs abs >lutely nothing, The 
cost of maintenance of a turbine is only interest 
on first cost, repairs, lubrication and very little 
attendance. The maintenance of the conducting 
wire* is purely interest on capital ; and of the 
dynamo as the turbine ; and we have the total 
ooet. Turbines and dynamos alike have no recipro- 
oating motions and are, therefore, mechanically 
speaking, very easily kept in order if conscientiously 
oonstruoted at first. 
A boiler and steam engine, as I pointed out in a 
previous letter, have in them the elements of con- 
siderable expense for repairs and attendance and 
require fuel. Tho latter, when fallen timber is un- 
obtainable, is of course an item of considerable 
importance. 
Your artiole, amoDg its objections to the pro- 
posed utilisation of electricity, dealt with the low 
efficiency of electrical transmission. Both turbines 
and dynamos are maohines of very high efficiency. 
A good turbine will go up to over 80 per csnt, 
a good dynamo to 90 per cent, a good motor over 
90 per cent. The loss in the wire (whioh is ex- 
pended in heat, and cannot be spoken of as friction) 
depends ou the distanoe and the system adopted. 
Assuming this 10 ptr cent, the efficiency of the 
system is 80 % x 90 % x 90 % x 90 % or over 58 % 
and all these figures are below what has been 
done. But even if the loss were considerably more, 
where the original power oosts nothing the effici- 
ency is of little importance. 
It appears at first sight rather strange that dynamo 
machines began with (alternating currents, and 
electricity made very little progress wilh them. 
Siemnes and Gramma introduced direct current 
machines, Swan and Edison produced the inoan- 
descent lamp, (which had been invented but not 
made a practical succ3ss a generation befors), and 
electricity advanced by leaps and bounds. Then 
it was fojnd that the transmitting of eleotricty 
over long distances on the direot current system 
brought to light a number of unexpected difficul- 
ties, and inventors turned their attention to 
alternating currents again. The great advantage 
of alternating currents is the facilities they give 
for the economical transmission of electricity, but 
it ia only within recent years that it has been 
found practicable to use alternating currents for 
driving electro motors. It would take a considerable 
exp?nditure of time, ink and paper to try to explain 
how this is done, but it may be worth mentioning that 
two years ago on the Continent about 100 horse posver 
was successfully transmitted about 100 miles over 
3 wires less than £ of an inch in diameter. I 
regret that not having the necessary books of 
reference to consult I am forced to quote these 
figures from memory. Perhaps one of your cor- 
respondents may be able to give the exact faots. 
In this experiment the electricity generated near 
the fall was " transformed " into " high potential " 
eleotrioity, to pass over the wire, which was again 
transformed into eleotricity of manageable " poten- 
tial '' when the current was passed into the motors. 
As the high potential eleotricity might have been 
fatal to any iojudioioue meddler, the line of route 
was profusely embellished with representations of 
death's heads and warning notices. 
A little of this and a few demonstrations '• pour 
encourager les autres " on pariah doge, and a 
oareful arrangement of oblique spikes pointing 
downwards on the supporting poles would proba- 
bly render the wires safe from the depredations 
of native thieves, a possibility quoted ia one 
of your articles. Who would I should imagiae 
be very chary of provoking the demon of 
the " pUari kambi?" If the direot current system 
were used the distance would be short and 
surveillance easy. Besides if the possibilities 
of theft were a matter of great impor- 
tance, it might be practioable to substitute iron 
wire of one-seventh the conductivity of copper 
and less than one seventh the price. As 
far as secondary batteries are concerned the 
planter in districts beyond the reach of skilled 
labour would be well advised to keep clear of 
them, as a somewhat expensive luxury. Few 
contrivances of their olass have so many different 
ways of unobstrueive shirking of their work. 
Yours, &e., — J. 8. 8. 
Deab Sut,— Your correspondent "J. 8.8." write* 
with the ease and fluency cf an expert on this 
subject, and now that electrical tramways have 
been sanctioned for Colombo and may scon be in 
operation here, the public will do doubt take a 
greater interest in the subjeot ; but as they are not 
technically posted and fir from omnisoient, I and 
probably others would be glad to hear again on 
the subjeot from your correspondent. 
I observe that in his second paragraph he just 
glanoes at the new theory of Eleotricdl Transmission 
recently explained by Dr. J. Larmor f.b.b., to the 
effect that " an electrical disturbance is conveyed 
by the ether just outside the wire with the 
velocity of light, and the wire itself has absolute 
negative qualities, merely guiding the disturbance 
from one end to the other as it prevents the 
ethereal vibrations from being dis ipated through 
space." This theory I think, upsets much that 
has hitherto been taught in explanation of current 
loectrioity through wires ; but what tht so-calkd 
"ether" itself is has not yet been learned and 
cannot be explained. We were always taught 
that it pervaded all space and all matter, 
and that it flowed like a breeze through the 
densest metal. If this were bo, I do not see 
why the electrical disturbance should not pass 
by the ether in the wire as well as by that 
immediately surrounding it, but I have n t Dr. 
Larmer's full text before me, though "J. S. 8.' 
probably could clear up this difficulty. 
In an article on " Motive Power for Tea Estates" 
(ipril 27th) you noticed Mr. Rutherford's sup- 
posed objections to the distribution of power by 
electrical transmission from central sources. These 
objec'.ions " J. S. S." shows us how to overcome; 
and it would be well if our various Planters' 
Associations took note of thi?, end fixed upon 
suitable nl»ces in th6 various cistiicts where 
water power is available and central enough to 
supply as many estates with power by e ectrio&l 
transmission from a turbine u« car« to join in 
the cost of its installation and maintenance. 
Your correspondent also notices the objections 
to elestrioal motors on account of the " low effi- 
ciency of electrical transmission " as contained 
