1.
2.
3.
4.
5.
6.
7.
8.
9.
32


V.-VI.
COMPARISON


OF


THE    OLD    FRENCH    BAROMETER


WITH


THE    ENGLISH    AND    THE    METRICAL    BAROMETERS,


OR


TABLES

FOB,   CONVERTING   FRENCH   OR   PARIS    LINES    INTO   ENGLISH  INCHES
AND   DECIMALS,   AND   INTO   MILLIMETRES;

GIVING    THE    VALUES    CORRESPONDING    TO    EVERY   PARIS    LINE   FROM    120    TO    216

LINES,    OR    FROM    10    TO    18    INCHES  ;   AND    TO    EVERY   TENTH    OF   A   LINE

FROM   216    TO    348    LINES,    OR   FROM   IB    TO    29   FRENCH   INCHES.
33


TABLE    V.
MM.  J.  J.  Pohl  and  J.  Schabus  have  published,  in  the  number  for  March,  1852,
of  the  Proceedings  of  the  Imperial  Academy  of  Vienna,  Class  of  Mathematics  and
Natural  Philosophy,  a  set  of  short  Thermometrical  and  Barometrical  Reduction
Tables,  among  which  is  found  a  table  for  the  reduction  of  the  Old  French  Baro-
metrical Scale  into  the  English.  As  this  table  shows  slight  discrepancies  from  the
one  given  in  the  following  pages,  it  may  not  be  out  of  place  to  state  that  they  arise
from  an  accidental  error  in  the  equation  used  by  MM.  Pohl  and  Schabus  in  com-
puting their  table.  Adopting,  as  they  do,  Bird's  value  of  the  metre,  viz.
1  metre  =  39.37062  English  inches,
the  value  of  the  Paris  line  is

1  Paris  line  =  0.088813  English  inches.
But  the  table  seems  to  have  been  computed  by  using  the  equation

1  Paris  line  =  0.088823  English  inches,
which  gives,  at  the  end  of  the  table,

348  lines  X  .088823  =  30.9104  English  inches,
instead  of

348    "      X  .088813  =  30.9069


thus  causing  an  error  =    0.0035

which,  of  course,  gradually  diminishes  in  lower  numbers.
34


V.       COMPARISON    OF    THE    OLD    FRENCH    AND    ENGLISH    BAROMETERS.
|

1  Paris  Line  =  0.088814  English  Inch,


French  or
Paris

Lines.
Tens.
!
Units.
0.
1.
2.
