50 
THE TROPICAL 
AGRICULTURIST. ^Avg. 1, 1899. 
hot from start to finish, and by this means it ia 
asserted that, after a few additional experiments, 
it will be possible to make tea of a penny per lb. 
higher value tlian by the old process, which besides 
the savini? of time and fuel, would naturally, amply 
rep?»y find additional ova, !riy in machinery. There 
is the further valuable consideration that instead of 
an expensive three-storey factory a si a", pie shed of 
cine floor will sufliee to acconirnodate the machinery 
for the manufacture of any quantity of teoj Estates 
it is expected, will send down leaf to be experimented 
with as a practical way of testing what is claimed 
for the new method in improving prices. At the 
end of the office a laboratory haa been fitted up in 
which chemical tests are carried on, and where 
with a powpvful little miscroscope the leaf is exa- 
mined in the various stages of manufacture. 
THE "liEVOLUTION " IN FANS. 
Perhaps the most inerenions of all the new things 
to be seen at Messrs Davidson's W ork^, however is 
the fan. This v/as described in a letter in our paper 
of the 28th March, and the first shipment of 18 
ventilating fans arrived by the last Bibby steamer. 
These had been preceded by two fans for smoke 
chimneys, one of which has been sent to Ba,langoda 
for Messrs. Finlay, Muir & Co., and the other is goin^ 
to one of tVie Haputale estates of Lipton, Limited. 
The eighteen ventilating fans were all of 30 and 35 
inches diameter ; and last night the remaining eight 
were booked — two by one firm, and six by another 
the orders being for two fans in each factory. 
Another shipment is expected by the next Bibby 
steamer, when various sizes, from 16 inches to 35 
inches, of the ventilating fans v.'ill come to hand. 
The new fans have not been advertised at home as 
yet, because, although the number turned out at 
Belfast is dnily in^'reasing, the existing demand can 
hardly be coped with. Before long, we are informed, 
25 a day will be piodnced, and th"n the invention 
will be extensively advertised, avid the p'oriuction 
will be increased as quickly as possible to 100 per 
day. A contract has been obtained for the ventilation 
and cooling and heating, of the Law Courts in 
London, which have always been in an unsatisfactory 
atmospheric condition ; and the fans are to be used 
in* connection with the scheme, which involves a 
seperate plant for each court with refrigerating and 
heating apparatus for winter and summer respectively. 
The air will also be filtered, so that fog and other 
impurities may not enter. In addition to this the 
ventilation of the House of Commons is to be similarly 
improved; and exhaustive experiments were to 
be made a week or two ago by the Admiralty to see 
whether the new instruments did what was claimed 
for them, in which case Sir William White, the Chief 
Director of Naval construction, had declared they 
would be adopted at once through out the new 
vessels of the Navy. Information of the result of 
these tests has not yet come to hand. The flax and 
linen industry of Russia, which had been considerably 
pushed in recent years, and which requires fans for 
the benefit of the work people, has also produced a 
wonderful demand for the new patent, which we are told 
has been ordered in such numbers that the Russian 
market alone constitute a very important element. It 
is in Ceylon, however that the fans have been first 
advertised and fiist erected in different factories. 
To desciibe the fan, one of which, 80 inches in 
diameter, ia already in position and working at the 
Maradana establishment, we may say that it involves 
an entirely new idea in practical engineering. The 
fan hitherto familiar to the public possessed blades 
extending from the circumference to the centre and 
it. follo'.vs, as a fact, that the maximum amount of 
work done by each blade is at the circumference, 
the force being lessened gradually until the centre 
ia reached, where there is very little speed at all. 
Thus with any opposing pressure the efficiency of 
the old fan is greatly reduced, and air may even 
pass the opposite way through the centre, while the 
blades are doing their work at the outer edge. 
Davidson's patent may be described as shaped like 
a revolving squirrel cage, the blades being all of 
equal length round the circumference, and thus per- 
forming equal work throughout. By the same arrange- 
ment the space for the passage of air is as large as the 
fan itself, and the result is evident even to the lay 
mind, and is a marvellous advance on the old idea, 
an interesting feature is that the principle involved 
in the construction of the blades is in agreement 
with the contsntions of professors, but contracts with 
the experience of engineers in all other fans; and. 
the new vindication of the scientific theory is to_ be 
shortly discussed at the Institute of Mechanical 
Engineers. The advantage of the machine is that, 
while the air emerges with greatly increased force 
it enters in a regular and even manner, producing 
no disturbance in the vicinity. The air in fact ia 
drawn from all directions as powerfully as from 
immediately in front, and thus a much greater aiea 
of space is under its action. The regulari;y of the 
entiance of the air was also shown when a funnel 
was fixed to the bracket which holds the fan. The 
atmosphere rushed into this in a full and regular 
steam, indicating the. fan's great capacity for dis- 
posing of an unusual volume of air in a given time 
The speed was tested at various distances and 
from various directions by an anemometer, and 
established the inventor's contention. The fan wag 
then running, driven by a belt, at 380 revolutions 
a minute, and 10,584 cubic feet of air per minute 
were being drawn through. This entered at the rate 
of 2,000 feet, but was ejected on the other side 
at the rate of 5,530 feet, when reversed the fan 
does nothing. It may also be mentioned that 
the bracket holding the fan has the shaft sus- 
pended like the asle of a bicycle, and the two bearings 
are ia one piece, so that even if carelessly erecied 
by an inoxperieuced person, they cannot be put up 
out of line. On the outside a solid disc prevents 
high wind, or even a cycl.ine, disturbing its efficiency; 
and the air is discharged with equal force on all 
sides. The force of this air can be utilised for an 
upper loft by the fan being enclosed and the air 
conducted to the storey above The power used wtl 
0 ly about j h. p. 
Close by the fan already in position preparations 
were going forward for the erection of a still larger 
fan, to be completed by this afternoon. Although no 
harm would result, it would be waste of energy to 
over-drive a small fan, and according to the amount 
of v/ork to be accomplished, machines of C2rtain 
diameters are recommended. Mr. MaGnire further 
explained that the fans can be driven by electric motor 
and by water power, with new Pelton wheels recently 
patented by the inventor of the fan. A volume of 
photographs further shows the variety of uses to 
which the invention can be put ; and other pictures 
represent some highly interesting tests, one of which 
in competition with one of the older style of fans of 
three times its area wa« fully decribed in our issue 
of the 28th March,— Local " Times." 
Coffee — The Moniteur des Interets Mat^rieh 
says the coffee crop of 1895 with 6,500,000 hag-i 
realised £25,000,000. The result induced increased 
production, but iu 1897 the exportation of 
9.500,000 bags only brought in £10,000,000, and 
the 10,000.000 bags iu 1898 only realised 
£15,000,000. 
The Municipality of Bariry, S Paulo, has 
about five millions of coflFee trees planted of various 
ages. Its first crop will he oatliered this year, 
which is estimated at L50,000 ariobas of coffee. 
A coll'ee plantation at Mococa, Sao Paulo, was 
recently so'.d at judicial auction for the sum of 
90,000.':; its valuation being 202,000$. Ti.e planta- 
tion contained 112,000 coffee trees, 5,000 arrobaa 
of [licked coffee, coffee-cleaning machinery, build- 
ings, saw mill, etc., etc. It looks like a decided 
sacrifice. — Eio News. 
