The  Institute  figures  for  a  hardness  impression  taken
transversely  of  the  rolling  direction  gives  a  coefficient  of
0-366,  and  when  the  impression  is  taken  in  the  rolling
direction  a  coefficient  of  0  •  354  ;  and  for  hardness  numbers
above  175,  0-344  and  0-324  respectively.  These  Brinell
numbers  being  multiplied  by  the  coefficient  give  the
ultimate  tensile  strength  of  the  material  in  kilos  per
square  millimetre.
A  Brinell  Testing  Machine.— The  original  machines  for
this  work  being  of  a  costly  nature,  a  Stockholm  firm,
Aktiebolaget  Alpha,  have  placed  upon  the  market  a  com-
paratively simple  and  inexpensive  apparatus,  which  should
enable  a  great  number  of  engineering  concerns  to  carry
out  the  ball  tests  in  their  own  works.  It  consists  of  a
small  hydraulic  press,  exerting  its  force  downwards.  At
a  convenient  height  is  situated  the  anvil,  the  position  of
which  is  adjustable.  The  two  chief  parts  are  mounted
upon  a  substantial  cast-iron  frame.  The  lower  end  of  the
ram  carries  the  10  mm.  hard  steel  ball,  before  alluded  to.
Pressure  is  applied  by  means  of  a  small  hand  pump,  and
the  kilogrammes  are  shown  upon  a  dial,  directly  above  the
ram.  By  means  of  an  ingenious  preloaded  attachment,
the  machine  can  be  set  for  the  exact  pressure  required  to
be  exerted  upon  the  ball,  and  this  amount  cannot  be
exceeded.
