Section 291. Recording of conveyances

A conveyance of real property,
  within the state, on being duly acknowledged by the person executing the
  same, or proved as required by this chapter, and such acknowledgment  or
  proof  duly  certified when required by this chapter, may be recorded in
  the office of the clerk of  the  county  where  such  real  property  is
  situated, and such county clerk shall, upon the request of any party, on
  tender  of the lawful fees therefor, record the same in his said office.
  Every such conveyance not so recorded is void as against any person  who
  subsequently  purchases or acquires by exchange or contracts to purchase
  or acquire by exchange, the same real property or any  portion  thereof,
  or  acquires  by  assignment the rent to accrue therefrom as provided in
  section two hundred ninety-four-a of the  real  property  law,  in  good
  faith  and  for  a  valuable  consideration,  from  the  same  vendor or
  assignor, his distributees or devisees, and whose  conveyance,  contract
  or  assignment  is  first duly recorded, and is void as against the lien
  upon the same real property or any portion thereof arising from payments
  made upon the execution of or pursuant to the terms of a  contract  with
  the  same vendor, his distributees or devisees, if such contract is made
  in  good  faith  and  is  first  duly  recorded.    Notwithstanding  the
  foregoing,  any  increase in the principal balance of a mortgage lien by
  virtue of the addition thereto of unpaid interest in accordance with the
  terms of the mortgage shall retain the priority of the original mortgage
  lien as so increased provided that any  such  mortgage  instrument  sets
  forth its terms of repayment.