1881?  "According to the old traditions and customs--the Mosaic Law of the Esquimaux, so to speak--no work of any kind; except the drying of them, can be done upon new skins until the ice has formed sufficiently thickly upon the salt water to permit the hunter to seek the seal at his agloo or blow-hole." 
1959  He does this by going from one hole, or aglu, to another, to keep the holes open as the ice freezes.