th ▁the ▁cost ▁of ▁a ▁horse - dra wn ▁combine . ▁Forest ers ▁soon ▁adapted ▁them ▁to ▁ha ul ▁red wood ▁logs ▁out ▁of ▁road - less ▁for ests . ▁By ▁ 1 8 9 7 , ▁the ▁company ▁had ▁about ▁ 2 0 0 ▁employees ▁and ▁had ▁sold ▁over ▁ 8 0 0 ▁of ▁their ▁combined ▁har vest ers ▁in ▁California . ▁Hol t ▁Man ufact uring ▁made ▁about ▁ 1 3 0 ▁steam - power ed ▁tra ctors ▁between ▁ 1 8 9 0 ▁and ▁ 1 9 0 4 . ▁ ▁The ▁steam ▁tra ctors ▁were ▁extremely ▁heavy , ▁sometimes ▁we igh ing ▁ ▁per ▁horse power , ▁and ▁often ▁s ank ▁into ▁the ▁rich , ▁soft ▁earth ▁of ▁the ▁San ▁Jo aqu in ▁Valley ▁D elta ▁far ml and ▁surrounding ▁Stock ton , ▁California . ▁Hol t ▁tried ▁to ▁solve ▁the ▁problem ▁by ▁increasing ▁the ▁size ▁and ▁width ▁of ▁the ▁whe els , ▁but ▁this ▁also ▁made ▁the ▁tra ctors ▁increasing ly ▁complex , ▁expensive ▁and ▁difficult ▁to ▁maintain . ▁One ▁tra ctor ▁had ▁whe els ▁ ▁tall ▁and ▁ ▁wide , ▁producing ▁a ▁tra ctor ▁ ▁wide . ▁Hol t ▁could ▁spend ▁hours ▁in ▁his ▁private ▁work shop , ▁and ▁experiment ed ▁by ▁adding ▁multiple ▁whe els ▁and ▁ultimately ▁with ▁a ▁track - lay ing ▁technique . ▁ ▁First ▁work able ▁craw ling ▁t read ▁▁ ▁Many ▁people ▁had ▁attempted ▁to ▁add ▁tracks ▁to ▁moving ▁machines . ▁Over ▁ 1 0 0 ▁pat ents ▁had ▁already ▁been ▁issued