﻿604 
  Mr. 
  J. 
  Satterly 
  on 
  the 
  Amount 
  of 
  

  

  The 
  area 
  of 
  the 
  three 
  portions 
  of 
  the 
  circle 
  enclosed 
  in 
  this 
  

   triangle 
  = 
  half 
  the 
  area 
  of 
  cross-section 
  of 
  a 
  wire 
  = 
  7ra 
  2 
  /2. 
  

  

  .*. 
  area 
  of 
  cross-section 
  of 
  one 
  tube 
  

  

  = 
  a 
  2 
  ( 
  V3-7T/2) 
  = 
  -161a 
  2 
  . 
  

  

  .*. 
  fraction 
  of 
  whole 
  cross-section 
  which 
  is 
  tubular 
  

  

  •161 
  

   1-732* 
  

  

  Now 
  area 
  of 
  cross-section 
  of 
  the 
  annular 
  space 
  occupied 
  

   by 
  the 
  tubes 
  

  

  = 
  |{2-62 
  2 
  --43 
  2 
  } 
  = 
  5'25 
  sq. 
  cms. 
  

   .-. 
  Total 
  cross-section 
  of 
  the 
  tubes 
  

  

  '161 
  k 
  OK 
  iO 
  

  

  = 
  ^^2 
  x 
  = 
  sq 
  ' 
  cm 
  * 
  

  

  To 
  calculate 
  the 
  number 
  of 
  wires 
  required 
  on 
  the 
  

   assumption 
  that 
  they 
  are 
  as 
  closely 
  packed 
  as 
  possible 
  we 
  

   note 
  that 
  with 
  each 
  wire 
  there 
  is 
  associated 
  two 
  tubes, 
  and 
  

   since 
  total 
  cross-section 
  required 
  per 
  wire 
  and 
  two 
  tubes 
  

   = 
  2a 
  2 
  \/3 
  the 
  number 
  of 
  wires 
  

  

  5*25 
  

  

  l~) 
  

  

  177. 
  

  

  (t) 
  

  

  As 
  a 
  matter 
  of 
  fact 
  no 
  more 
  than 
  154 
  tubes 
  could 
  be 
  

   placed 
  inside 
  so 
  that 
  the 
  appproximate 
  total 
  cross-section 
  

   of 
  the 
  tubes 
  is 
  greater 
  than 
  '48 
  sq. 
  cm. 
  For 
  the 
  total 
  

   cross-section 
  of 
  154 
  wires 
  

  

  = 
  154 
  x 
  | 
  X 
  (-185) 
  2 
  

  

  = 
  4*14 
  sq. 
  cms. 
  

  

  .*. 
  total 
  cross-section 
  of 
  the 
  tubes 
  

  

  = 
  5*25 
  — 
  4-14 
  = 
  1*1 
  sq. 
  cms. 
  

  

  Taking, 
  then, 
  1*0 
  sq. 
  cms. 
  as 
  the 
  total 
  area 
  of 
  cross-section 
  

   of 
  the 
  tubes 
  and 
  half 
  a 
  litre 
  a 
  minute 
  or 
  8*3 
  c.c. 
  per 
  sec. 
  as 
  

   the 
  usual 
  rate 
  of 
  flow 
  of 
  air 
  during 
  the 
  experiments 
  the 
  

   velocity 
  of 
  the 
  air 
  through 
  the 
  tubes 
  is 
  8 
  cms. 
  per 
  sec, 
  and 
  

  

  