Oct.  r,  1895. J 
THE  TROPICAL  AGRICULTURIST. 
251 
CHEAP  TUANSrOHT  AND  HOW  TO 
GET  IT.— NO  6. 
CURVE  AND  GAUCyv 
Tlie  destructive  factors  whiclicome  into  operation 
during  the  movement  of  a train  round  a curve 
are:  (1)  the  thrust  of  the  leading  outside  wheel 
against  the  head  of  the  rail  due  to  tlie  centri- 
fugal swerve  of  the  train  ; (2)  the  nip  arising 
from  the  oblique  position  of  the  wheels  relatively 
to  the  rails ; (3)  the  sliding  of  the  wheels 
owing  to  the  outer  rail  being  longer  and  the 
inner  rail  shorter  than  the  centre  line ; (4)  the 
crushing  due  to  the  load  being  thrown  on  to  the 
inner  rail  by  the  elevation  of  the  outer  one.  It 
is  not  to  the  credit  of  railway  engineers  that 
the  manner  and  degree  in  which  these  factors 
are  affected  by  gauge  should  be  still  tlebatable. 
The  chaotic  state  of  opinion  and  the  lack  of  as- 
sured knowledge  hereupon  were  aptly  illustrated 
in  the  course  of  the  controversies  which  arose 
over  the  Nawalapitiya  extension : we  continue 
to  take  our  examples  as  far  as  possible  from 
Ceylon.  Writing  under  date  November  11th 
1874  Sir  C.  H.  Gregory  said  “ I do  not  consider 
that  the  existence  of  5-chain  curves,  if  unavoid- 
able, would  be  a bar  to  the  use  of  the  gauge 
ot  5'6";”  adding  later,  “to  work  properly  on 
inch  curves  special  appliances  would  be  required 
both  in'  engines  and  rolling  stock,  such  as 
shortening  the  wheel-base  and  the  use  of  radial 
axles  or  bogies  * * * these  are  no  novelty,  and 
the  result  of  theii  use  is  an  ascertained  fact, 
ainl  not  a speculative  question  depending  upon 
experiments  to  be  made.”  But  the  local  rail- 
way staff  were  of  a different  mind,  and  the 
Director  of  Public  Works  (Mr.  J.  11.  Mosse), 
fearful  lest  the  adoption  of  5-chain  curves  should 
eventuate  in  break  of  gauge,  and  convinced  of 
the  po.ssibility  of  securing  at  a slight  additional 
cost  a limiting  radius  of  6'37  chains,  sent 
in  to  the  Colonial  Secretary  an  elaborate 
statement  of  his  views  on  the  subject,  supporting 
them  by  quotations  from  a formidable  array  of 
authorities.  Amongst  them  Sir  Guildford  Moles- 
worth  to  whom  he  had  submitted  the  following 
questions  on  the  point  in  issue  between  himself 
and  Sir  C.  H.  Gregory: — “ Have  you  practical 
experience  on  the  State  Railways  in  India  of 
curves  of  3.30  feet  (=  5 chains)  on  a long  gra- 
dient of  about  1 in  44?  Do  you  know  of  any 
means,  by  radial  axle-box  or  the  like,  of  adapting 
ing  rolling  .stock  on  a gauge  of  5'  6"  to  curves 
of  330'  radius  ?”  To  which  Sir  Guildfoiil  Moles- 
worth  rejilied: — “ We  have  no  practical  experi- 
ence of  curves  of  333  (sic.)  on  a long  graclient 
ami  I sincerely  hope  we  shall  have  none  either 
on  a gradient  or  otherwise*  * * I know  of  no 
method  by  means  of  radial  axle  boxes  which 
would  lessen  the  friction  so  as  to  re- 
concile me  to  curves  to  anj'  extent 
of  330'  radius.”  Nearly  twenty-  years  have 
gone  by,  and  thousands  of  miles  of  railway  on 
all  kimls  of  gauges  to  all  kinds  of  curves  have 
been  built,  since  Messrs.  Gregory  and  Moles- 
worth  thus  darkened  one  another's  counsel,  yet 
there  is  well  nigh  as  much  room  for  dissidence 
now  as  then. 
All  wc  know  assuredly  is  :— First,  that  the 
resistance  duo  to  curves  is  mindi  greater  than 
would  appear  from  Moriison’s  stale  formula, 
still  given  in  Molesworth’s  “ Pocket  Book,”  ac- 
cording to  which  the  mea.sxrre  of  the  resistance 
is  the  figure  obtained  by  dividing  the  j)roduct 
of  weight  of  vehicle,  co-elficient  of  friction  of 
wheel  on  rail,  and  gauge  plus  wheel-base  by  twice 
the  radius  of  curve.  Second,  that  with  a wheel-base 
the  same  multiple  of  the  gauge  (and  it  should  not 
be  less  than  twice),  the  destructiveness  of  anj' 
given  curve  is  less,  the  less  the  gauge.  Hence 
it  is  that  to  accommodate  broad  gauge  rolling 
stock  to  sharp^  curves,  or  (keeping  to  the  particular) 
to  enable  6'  6"  wagons  to  run  round  5-chaiu 
curves  without  absolutely  ruinous  wear  and  teai', 
the  wheel-base  must  needs  be  contracted  to  the 
dimension  appropriate  to  metre  rolling  stock, 
namely  7 feet^  or  thereabouts.  Even  so,  the  wear 
and  tear  continues  greater  on  the  bi'oader  gauge 
by  the  amount  due  to  the  heavier  axle-load, 
speed  being  the  same.  Oil  the  curve  tlie  ex- 
pedient is  all  to  the  bad,  because  vehicles  whose 
wheel-base  is  much  under  twice  the  gau^e  have 
a tendency  to  travel  askew  and  spread  the  track  • 
they  swerve  now  to  this  side,  now  to  tliat’ 
striking  the  rail  laterally  with  a force  propor- 
tioned to  their  momentum. 
Let  us  get  to  figures.  According  to  Mellen 
ellington’s  calculations,  the  destructiveness  of 
a 5-chain  curve  per  ton  of  train  weight  would 
be  61  per  cent  less  on  a metre  than  on  a 5'  6" 
gauge  with  a wheel-base  in  both  cases  approxi- 
mately twice  the  gauge.  And  the  same  author’s 
experiments  on  the  New  York  Pennsylvania  and 
Ohio  railway  gave  the  following  noteworthy 
results:  on  two  locomotive  sections  of  equal 
mileage,  with  the  .same  rolling-stock  load, 
the  one  virtually  straight,  the  other  con- 
sisting for  one-third  its  length  of  curves  of 
6‘37  chains  radius  and  for  the  remaining  two- 
thirds  virtually  straight,  the  locomotive  expenses 
alone  during  the  trial  year  were  7 per  cent 
greater  on  the  curved  than  on  the  straight.  The 
gauge  was  4'8|."  A similar  series  of  experi- 
ments on  the  Ceylon  5'6"  track  should  show  that 
locomotive  expenses  are  at  least  12  per  cent 
higher  on  sharp  curve  sections  than  on  straight; 
inoliably  more,  on  account  of  the  higher  degree 
of  friction  which  obtains  in  climates  like  that 
of  Ceylon.  The  heavier  wear  and  tear  caused  by 
curvature  is,  of  course,  not  confined  to  the 
locomotive ; it  is  felt  in  almost  every  item  of 
operating  expenses,  notably  in  maintenance  of 
the  track.  Locomotive  expenses  are  singled  out 
merely  because  the  difference  may  be  more  readily 
and  accurately  mea.sured.  The  third  item  of 
certainty  in  the  matter  of  curve  and  gauge  is  that 
in  broken  country,  the  shorter  the  limiting  radius  of 
curve  the  less  the  cost  of  construction;  and  (re- 
peating what  we  have  already  said)  the  narrower 
the  gauge  the  less  the  danger  .and  damage  accruino- 
from  this  .source  of  economy.  Lacking  better 
argument,  the  narrow-gaugers  on  the  occasion  of 
a famous  te.st  run  over  the  “seven  foot  way” 
from  Didcot  to  Goring,  privily  abstracted  the 
grease  from  Brunei’s  axle-boxes.  Under  a similar 
necessity  the  broad-gaugers,  Messrs.  Haivkshaw 
and  Bidder  for  example,  have  denied  both  these 
propositions,  or,  to  be  quite  accurate,  they  have 
lielittled  the  saving  to  be  effected  by  sharpening 
the  characteristic  curve,  and  have  .affirmed  th.at 
where  a little  railway  can  go,  there,  and  n-ith 
equed  case,  a big  raihvay  can  go  also.  To  such 
amazing  statements  Avere  truthful  church-o-oim.- 
men  driven  a quarter  of  a century  ago  in  'their 
laud.ablc  endeaveurs  to  prevent  lireak  of  gaii-m. 
Sir  C.  H.  Gregory  on  the  contrary  (and^’tliese 
samples  of  the  extent  to  which  opinion  takes 
the  jihace  of  .ascertained  fact  in  r.ailway 
practice  c.aniiot  be  too  carefully  pondered) 
Sii  C.  H.  Gregory  Av.as  so  convinced' of  the  saviim 
which  might  be  effected  in  hill  country  by  shorteif- 
ing  up  the  limiting  radius  of  curve  by  even  a 
chain  that,  advising  on  the  Nawalapitiya  exten- 
tion,  he  wrote,  “if  a s.acrifice  of  eHiciency  must 
be  made  in  order  to  limit  the  cost  of  the  extension 
1.  hVefelt  tliat  the  sacrifice  of  the  curves  was 
