If understand you right.  Here in Ohio where I live there is alot of this type of older discriptions.  Your property is in Section #4.  There is 36 sections/fractions in a township of land. One section/fraction is 640 acres.  Mark it off in quarters.(supposedly square)  Now, you have the first NW 1/4. The top one on the left. (approx. 160 acres) now mark this quarter into quarters.  This is also the top one on the left. Containing about 40 acres.  (Northwest 1/4 of the Northwest 1/4).
I hope this is what you was wondering.