January i, 1889.] THG TROPICAL AGRICULTURIST. 
495 
(KoiiiiosponUonot'. 
To the Editor. 
DAVIDSON'S NEW " SIROCCOS." 
5th Deo. 18S8. 
Sin, — Coming from n planter, the following details 
concerning the latest improvements in "Sirocco Tea 
Driers'' will doubtless be interesting to many of your 
readers, to wbom I am tempted to offer them, owing 
to tboir intrinsic importance, which was mado so for- 
cibly manifest to mo at the first trial any planter has 
been permitted to witness, viz. at the Sirocco Works, 
J telfaet, last week. 
It is somewhat rash, perhaps, to pronounce a verdict 
based entirely upon one's own unaided impres ions in a 
matter of this kind ; but, speaking solely for myself, 
and with ail modesty, it is pormisMble to say that, I 
think that the last thing in " Siroccos," viz. the intro- 
duction of tho " Down Draft" principle, is the most 
important innovation which Mr. Davidson has intro- 
duced since ho first brought out his original " No. 1 
Sirocco." 
Before dealing with this new departure, however, it 
is as well to briefly notice the great improvements re- 
cently made in tho "T Sirocco" type of the old "Up 
Draft" principle. Apart from all the now minor va- 
riations in type, wo have henceforth to deal with va- 
riations in principle also, which is for the future divided 
into the two major divisions or classes, tho "Up Draft" 
(or old priuc'ple) and tho " Down Draft" (or new prin- 
ciple). At present there is only 1 type of the "Down 
Draft." Of the old " Up Draft," there are several 
I ypes as your readers are aware, such as the original 
"No. 1 Sirocco," the "T Sirocco" and its different 
pees, &0. The latest improved " Up Draft Sirocco" 
consists in such a blending of the " No. 1 Sirocco" with 
the " T Sirocco," as produces a novel "T Sirocco," 
called tho " Side-Drawer," embodying in itself all the 
advantages of its two parents, so to speak, whilst the 
least convenient features of both are omitted. In the 
in w " si, U - Drawer," the external shape is that of the 
" T Sirocco." Instead, however, of tho " T Sirocco" 
arrangement of the trays sliding through from end to 
end ol the drying chamber, these are now placed in 
sets of l trays as drawers, one above auother, as iu 
the " No. 1 Sirocco," and they draw out independ- 
ently of each other at the side of tho drying 
chamber over tho back part of the stove. This 
arrangement necessitated an alteration of the posi- 
tion ol tho " by-passes," these instead of being partially 
outside the drier as in the original "T Siroccos," 
are now arranged vertically between the different 
tiers of trays. The chimney's position is no longer 
at th back of tho drier, but alongside the fire-door. 
The auvautages gaiued by these alterations aro self- 
■ trident, but may bo briefly summarized as follows: 
The drier now requires a much shallower pit, whilst a 
free and open head-room for tho stoker is still 
maintained. The highest tray is iu eousequei aly 
I ft. 6 iu. from tho floor-levol, thus even i' 
with all the others, completo facility for rapid, . ., 
and convenient inspection. The form of tho drier is 
moro compact, whilst still retaining tho advantages 
M the t.y.passes " for conducting hot air to the 
upper trays. Last, but not least, the risk of scorch- 
ing n lot of the trays when, from aoy cause, a delay 
occurred in removing the end trav iu tho original T 
Sirocco typo is completely avoided. Tho stovo is 
provided with all the most recent improvements, and 
it-, life bus been iramcusoly extended by the now 
OUb-ixOD tiloi. I trust I have now justified tho 
opiuiou Hot forth above, that this Sirocco embodies 
in itself all tho advantages of its parents, whilst 
omitting tho least couvonient featuros of both. 
( Coming now to tho totally now Sirocco on the new 
Down Draft " principle. Thin is an innovation indued, 
in mom respect-, than one. Not ouly haa Mr. Davidson 
ror tho il r »t tiroo-apart from moro oxpt-rimouU— 
added "power '' lo bin Mroccos, in the loriu of a I 
power-ilnveu fan, but ho has turned the applioatiuu 
of bit draft upjido down, and now draws tho hot air ) 
downwards from above through tho tier of 8 trays, 
enclosed in the speciallyconstructed drying " chamber " 
of hia new " Down Draft Sirocco." A description of 
the apparatus itself I will not attempt, and for two 
reasons. Iu the first place, most of your readers will 
doubtless have already received au illustrated circular 
which sufficiently describes the apparatus ; so a des- 
cription here is a waste of force. In the second 
place any verbal description would fail to do justico 
to the extreme simplicity of this Sirocco. Suffice it, 
that it is most simple to erect, being sent out in 
largo sections, only requiring joining together ; and 
it is as simple to work as the " No. 1 Sirocco," with 
the additional convenience, that the mau working it 
never feels any radiated heat from it. Mark, I do 
not say that it is easy to work, as that would 
be incorrect. It is simple, yes, as siraploas would be 
wished, but its appetite is such that to feed it to 
tho capacity thereof will tax two coolios to the full 
powers of endurance which could reasonably be ox- 
pected in them for a whole working day. It has 
8 trays, and as fast as two coolies can properly spread 
the charge of green leaf on these, so fas' almost will 
it dry them off ! It takes 8 minutes from the in- 
sertion of a tray of rolled leaf at the " inlet port " 
below, to its withdrawal as dry tea at the outlet port 
above. It will bo hardly necessary to call attention to 
what this rapid rate of firing means in tho matter of 
improved quality of outturn. Wheu tea is not thus 
very rapidly dried, allowance in the ''fermentation" 
has to be mado for that much '' fermentation " which 
will certainly go on during the drying, until it is 
checked by tho heat. Considerable uncertainty is 
attached to this, as the condition of the leaf, and of 
the temperature of the drier &c.,&c, have to be taken 
into accouut, and that part of the " fermentation " 
which takes place in tlie drier not being under actual 
observation, is open to serious variation and inequality. 
Mr. Davidson started upon the accepted view, that 
an ideal tea drier must check " fermeutatiou " iu the 
shortest possible space of time, thus allowing the 
change of colour iu the leaf during " fermentation " to 
be kept under actual observation, outside the drier, to 
tho last moment before checking it ; and further, that 
this power of immediately checking " fermentation " 
must be at the same time free from any risk of scorch- 
ing or over-firiug. Starting with this ideal in view, ho 
believed that a comparatively low temperaturo was 
necessary to avoid the risk of over-firiug. To get the 
requisite rapidity in firing, he therefore resolved to 
rely upon the speed of the current of air employed to 
remove the damp absorbed by the warm air. Tho 
result is this new Sirocco iu which the temperaturo is 
never allowed to rise above the safe limit of 24ii\ and 
iu which the leaf is nevertheless completely dried iu 
8 minutes. Planters do not need to be reminded, that 
if leaf is completely dried in S minutes, " fermenta- 
tion " must have been checked iu a very much less 
time still. Hence, it is not going too far. to say that 
Mr, Davidson has attained his ideal, and as most will 
ntrreeto his definition of tho ideal, the advance he has 
i do will bo pleasant news, if the results with actual tea 
tally with those obtained at tho trials with thoroughly 
sodden, chaffed or chopped straw which I witnes.-oil, 
and which trials quite boro out the estimate given ou 
tho illustrated circular to which I have already alluded. 
That estimate, I tako it, is for aversge weather ; iu 
dry weather, so far as can be judged on this side, 
it may bo exceeded ; in very wet weather it may 
possibly hardly be reached. Ou the whole, it seems 
a fair and reasonable estimate, so far as can bo 
calculated here. Its suitability for '* fin il firing" beforo 
packing I saw tested with actual rmatf-lehfed tea ; 
and 200 lb. were passed through in 80 minutes, 
thoronghly well finished, although tho temperature 
was ouly at '.'30 degrees instead of the regulation 2-10 
degrees — hence, so far as final firing is concerned, tho 
estimate on tho circular worded as follows : — *' Final 
fir. s for packing about 5 maunds of whole leaf teas, 
or about 3 maunds of brokwu teas per hour," was 
moro than borne out, as tho temperature wan not up 
to full limit, tho loaf too was only about tbo siio of 
a leafy broken pekoe, and yet the work was turned 
