194 
Trials  of  Agricultural  Motors. 
Traction  Trials. 
The  traction  trials  were  commenced  on  Friday.  A circuitous 
route  of  12  miles  had  been  laid  out,  providing,  as  far  as  the 
locality  would  permit,  variable  conditions. 
Fig.  No.  8 is  a reduction  from  the  6-inch  ordnance  map  of  the 
course,  and  from  the  dotted  contour  lines  shown  thereon,  it  will 
be  seen  that  there  were  some  fairly  long  and  steep  gradients,  and 
though,  throughout  most  of  its  length,  good  roads  prevailed, 
there  were  stretches  of  by-road  and  cart-road  which,  had  the 
weather  been  a little  less  favourable,  would  have  presented  very 
considerable  difficulties  for  some  of  the  motors.  As  it  happened, 
however,  the  course  could  not  have  been  in  much  better 
condition;  the  trial,  therefore,  was  not  a severe  one  though  it 
fully  answered  its  purpose. 
Two  trailer  trucks  were  lent  by  Messrs.  Aveling  & Porter, 
and  each  competitor  declared  before  starting  what  load  he  would 
convey  twice  .round  the  course,  a distance  of  24  miles. 
The  motors  were  despatched  at  intervals,  each  being  in 
charge  of  an  observer,  who— in  order  to  ensure  uniformity  of 
observation — was  provided  with  a copy  of  the  map  of  the  course 
and  a previously  prepared  log  sheet  on  which  he  recorded  the 
load  hauled,  fuel  and  water  consumption,  the  time  occupied  on 
the  several  sections  of  the  route,  etc.  The  results  of  such 
observations  are  summarised  in  Table  No.  5. 
Brake  Trials. 
In  order  to  test  the  relative  powers  of  the  several  motors 
more  accurately  than  could  be  done  by  ploughing,  they  were  all — 
with  one  exception — tested  on  a dynamometer  brake,  similar  in 
principle  to  the  rope  brake  used  in  former  oil  and  gas  engine 
trials,  excepting  that  instead  of  having  the  brake  directly  on  the 
fiy-wheel  of  the  engine,  in  this  instance  two  brakes  were  mounted 
on  a countershaft  running  at  about  1,000  revolutions  per  minute, 
which  the  engine  drove  by  means  of  a belt.  Each  engine  had  to 
place  itself  in  position,  and  to  drive  this  countershaft  just  as  it 
would  if  driving  a threshing  machine. 
A record  was  kept  of  the  horse-power  developed.  The  fuel 
and  water  consumption  and  the  results  are  given  in  Table  No.  3. 
It  will  be  noticed  that  the  coal  consumption  is  given  at  per  brake 
horse  power  per  hour,  whereas  the  oil  is  given  in  gallons  per 
brake  horse  power  throughout  the  trial ; one  of  these  engines  not 
having  completed  an  hour’s  run. 
F.  S.  Courtney, 
25  Victoria  Street,  M.Inst.C.E. 
Westminster,  S.W. 
