Next  in  order  comes  the  cultivator.  The  first
cultivator  was  a  kind  of  crude  hoe  that  has  been
developed,  under  the  addition  of  animal  power,
until  we  have  machines  that  are  indispensable  to
the  cultivation  of  growing  plants.  The  4)rimitive
single-shovel  gave  way  to  the  double-shovel.  The
double-shovel  was  supplanted  by  the  straddle-row
cultivator,  and  even  the  latter  has  been  doubled
until  in  some  cases  it  is  adapted  to  take  two  rows
at  a  time.  Early  in  the  eighteenth  century,  Jethro
Tull  invented  a  horse-hoe  and  drill,  but  his  machine
never  became  popular.  The  double  shovels  used  in
this  country  until  the  year  1860  were  made  gen-
erally by  country  blacksmiths.  George  Esterly  took


Pig.  543.    Two-row  cultivator.
out  a  patent  on  a  straddle-row  cultivator  for  two
horses,  April  22,  1856;  this  was  the  first  of  the
line  of  implements  in  the  manufacture  of  which
millions  of  dollars  are  now  invested
It  will  be  impossible  to  describe  or  illustrate  all


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A  SYSTEM  OF  SCIENTIPIC  SOIL  CULTURE  FOR  SEMI -ARID  REGIONS


the  varions  types  of  cnltivators  found  on  the  mar-
ket. The  simplest  of  them  all,  omitting  the  single
and  double  shovel  cultivators,  is  the  four-shovel
walking  tongueless  cultivator,  similar  to  the  one
illustrated  in  Fig.  539.  This  is  a  cheap  tool  and  has
an  advantage  in  requiring  little  space  for  turning
at  the  ends  of  the  rows.  To  do  good  work  with  this
kind  of  cultivator,  it  is  necessary  for  the  team  to
work  very  evenly.
The  cultivator  in  Fig.  540  shows  a  tongue  and
also  is  provided  with  six  teeth  or  shovels.  Fig.  541
illustrates  a  good  type  of  riding  cultivator.  This


FlC.  544.  The  disc  coltiTator.
