Sept,  i,  1893.1 
THE  TROPICAL  AGRICULTURIST. 
*59 
of  advertising  notwithstanding  to  the  contrary.  The 
talk  about  the  “iron  in  the  soil"  of  Ceylon  and 
India  making  their  teas  more  wholesome,  may  deceive 
John  Bull,  but  Uncle  Sam  is  too  wide-awake  to  swal- 
low such  argument,  or,  indeed,  tea  which  requires  such 
“rot"  as  this  to  get  people  to  use  it. — American  Grocer. 
[ Virulent  talk  like  this  is  unworthy  of  the  Ameri- 
can Grocer.  Taste  which  has  changed  can  be  changed 
again  ; and  the  chief  advertiser  of  Ceylon  teas  is  an 
American,  Mr.  Elwood  May.  The  dealers  in  China 
and  Japan  teas  are  evidently  getting  alarmed.— Ed. 
T.A.~\ 
OIL-ENGINES  AS  MOTORS  FOR 
ELECTRIC  LIGHTING. 
A great  deal  of  attention  is  being  paid  by  the 
power  users  of  the  world  to  the  possibilities  which 
lie  before  petroleum. 
Petroleum,  it  is  well-known  exists  in  vast  quanti- 
ties in  many  parts  of  the  world.  The  supply  in 
South  Russia  appears  to  be  inexhaustible,  in  America 
and  other  places  there  would  seem  to  be  stores  of 
it  sufficient  for  all  wants  for  many  years.  Many 
people  have  thought  that  if  at  some  future  date 
the  supply  of  coal  should  run  short,  that  it  is  in 
petroleum,  we  should  find  our  most  convenient  sub- 
stitute. Owing  to  the  increasing  number  of  applica- 
tions to  which  it  may  be  put,  the  demand  in  the 
past  few  years  has  increased  enormously,  and  there 
are  now  a whole  fleet  of  specially  constructed  steam- 
ers engaged  in  the  trade  of  carrying  it  in  bulk  from 
one  place  to  another. 
These  facilities  for  cheap  transport  have  resulted 
in  the  cost  of  the  substance  being  reduced  to  about 
fourpence  per  gallon,  and  further  reductions  are 
talked  about. 
A few  weeks  ago  a process  was  shewn  in 
London,  by  means  of  which  cheap  qualities  of 
the  oil  may,  by  the  addition  of  some  easily  pre- 
ared  chemical  be  solidified,  and  these  blocks  may 
e transported  about  from  one  place  to  another 
like  coal,  burning  with  very  little  ash,  and  forming 
a very  convenient  and  cheap  form  of  fuel.  It  is 
stated  that  only  about  5 to  7 per  cent  of  the  oil  is 
wasted,  so  that  if  the  process  can  be  as  successfully 
carried  out  in  practice  as  the  experiments  already 
made  seem  to  indicate,  it  would  appear  certain 
that  such  a fuel  would  be  extensively  adopted  in  many 
parts  where  coal  is  too  expensive  to  be  freely  used. 
But  by  far  the  most  important  of  its  present  uses 
is  that  of  direct  power  development  in  an  internal 
combustion  engine. 
These  have  been  obtainable  for  some  few  years, 
but  it  is  only  lately  that  they  have  been  perfected 
and  manufactured  in  sufficient  numbers  to  be  recom- 
mended for  electric  lighting  work.  There  seems 
now,  however,  to  be  little  doubt  that  they  may  be 
thoroughly  relied  upon  for  dynamo-driving,  &c.,  in 
places  where  a steam-engine  and  boiler  would  be 
inconvenient,  and  gas  for  a gas-engine  is  un- 
obtainable. 
They  have  also  advantages  in  the  question  of 
cost,  for  we  find  Sir  James  Douglass,  f.r.s.  in 
a recent  discussion  at  the  Institute  of  Mechanical 
Engineers  stating  that,  after  an  experience  of  over 
twelve  months  with  a “ Priestman  ” oil-engine,  he 
found  that  it  was  cheaper  than  a gas-engine  at  the 
ordinary  prices  charged  for  coal-gas  in  England.  He 
thought  that  oil  certainly  was  coming  to  the  front. 
Messrs.  Priestman  Bros.,  Ld.,  of  Hull,  London  and 
Glasgow,  have  been  one  of  the  chief  pioneers  in  the 
perfecting  of  petroleum  motors.  They  have  spent 
years  in  experimental  work,  and  have  now  succeeded 
in  producing  a thoroughly  reliable  engine,  deriving 
its  power  from  ordinary  mineral  oil. 
As  a proof  of  how  important  this  invention  is  con- 
sidered, we  may  mention  that  a recent  meeting  of 
the  Institution  of  Civil  Engineers  was  occupied  with 
the  reading  of  a paper  by  Prof.  W.  C.  Unwin,  f.r.s., 
m.i.c.e.,  describing  various  experiments  he  had  made, 
and  tests  to  which  he  had  subjected  the  “Priestman" 
oil-engine.  He  stated  that  this  engine  was  the  only 
one  deriving  its  power  from  oil  which  had  stood  the 
test  of  practical  working  in  the  hands  of  various  users 
of  power.  The  tests  showed  that  the  engine  worked 
with  a very  high  thermo-dynamic  efficiency  and 
economy.  On  all  occasions,  when  he  had  been  using 
the  engine  he  had  been  able  to  start  it  without  any 
difficult)'. 
We  find  that  nearly  one  hundred  engines  of 
various  sizes  from  one  to  twenty-five  effective  horse- 
power are  already  in  use  for  driving  dynamos  in 
various  parts  of  the  world.  Owing  to  its  compact- 
ness and  the  fact  that  it  is  perfectly  self-contained, 
and  that  there  is  no  need  to  erect  steam-boilers  or 
anything  of  that  description,  it  is  especially  suitable 
for  isolated  installations.  There  are  also  several 
hundreds  used  for  other  purposes,  such  as  pumping, 
sawing,  air-compressing,  and  a large  variety  of  pur- 
poses connected  with  various  engineering,  manufac- 
turing, and  agricultural  appliances. 
Our  illustrations  Figs.  1 and  2 show  the  “ Priest- 
man" engine,  the  first  in  the  field,  and  the  kind 
manufactured  by  Messrs.  Priestman.  Fig.  1 illus 
trates  a three  horse-power  engine  with  a dynamo 
on  the  same  base.  The  working  of  the  engine  is 
very  simple.  Inside  the  foundation  there  is  areservoir 
for  the  oil,  which  is  forced  out  by  an  air-pump 
through  a spray-maker.  In  passing  through  this 
device,  the  oil  is  broken  up  into  a fine  spray.  In  this 
form  it  passes  through  the  vapouriser,  when  being 
further  mixed  with  air,  it  becomes  ready  for  admission 
into  the  combustion  chamber. 
The  piston  works  on  the  well-known  four-cycle 
movement. 
The  valves  are  of  the  ordinary  mushroom  pattern, 
the  inlet  valve  works  by  the  suction  of  the  piston’s 
outstroke,  and  the  exhaust  valve  is  opened  by  means 
of  a lever  from  the  countershaft,  and  kept  closed  by 
means  of  a spiral  spring.  There  are  no  slides  what- 
ever in  connection  with  the  engine,  which  are  often 
found  to  be  troublesome  in  gas-engines. 
Like  all  gas-engines  the  motive  power  is  obtained 
by  the  explosion  of  a mixture  in  suitable  proportions 
of  vapour  of  petroleum  and  air.  In  the  Priestman 
engine  the  explosion  is  caused  by  a spark  from  a small 
primary  battery,  though  where  a dynamo  is  driven  by 
the  engine,  a small  accumulator  may  be  employed  for 
the  purpose. 
Fig.  2 shows  a type  of  engine  which  has  been 
adopted  by  the  New  South  Wales  and  Victorian  Gov- 
ernments for  electric-lighting  work.  It  consists  of 
two  cylinders  and  is  of  25  horse-power,  the  working 
parts  being  very  compactly  arranged. 
Among  the  many  advantages  to  be  gained  by  the 
adoption  of  these  motors  may  be  mentioned  the 
case  of  fixing,  the  absence  of  all  subsidiary  build- 
ings, such  as  boiler-houses,  Ac.,  and  the  fact  that 
petroleum  being  such  an  easy  thing  to  move  in  bulk, 
the  distance  of  an  installation  from  a coalfield  or 
railway  station  need  not  be  taken  into  serious  con- 
sideration. 
They  seem  to  be  very  easy  to  manipulate  and  to 
require  little  skilled  attention ; in  many  farms  where 
they  have  been  adopted  in  England,  they  are  left 
solely  in  charge  of  the  ordinary  farm  servants  who 
seem  to  find  no  difficulty  with  them. 
The  cost  of  working  with  these  engines,  even  when 
the  sizes  of  engines  used  are  so  comparatively  small, 
comes  out  at  about  one  half-penny  per  brake  horse- 
power pel  hour,  a result  which  must  be  felt  to  be 
very  satisfactory,  when  all  the  advantages  of  the 
motor  are  taken  into  consideration. 
The  oil  is  stored  in  a tank  in  the  body  of  the  engine, 
and  only  just  the  right  quantity  is  admitted  at  a 
time  into  the  exhaust  chamber  from  which,  when 
mixed  with  the  proper  proportion  of  air,  it  is  passed 
into  the  combustion  chamber,  which  corresponds  to 
the  steam  cylinder  in  an  ordinary  steam-engine. 
Another  type  of  oil-engine  illustrated  in  Fig.  S 
is  manufactured  by  Messrs.  Crossley  Brothers  of 
Openshaw,  near  Macliester. 
It  is  of  more  recent  introduction  to  the  “ Priest- 
man,” and  is  really  an  adaptation  of  the  world-re- 
nowned “ Otto  ” gas-engine  for  using  oil.  It  is 
constructed  on  nearly  as  possible  the  same  lines  as 
the  “ Otto,"  the  petroleum  being  vapourised  and  the 
oil-gas  thus  generated  is  mixed  with  air  in  the  proper 
