Welcome to the forum.
S&W put the serial number on the butt, the back of the cylinder, the back of the yoke, the inside of the extractor star and the bottom of the barrel on the flat. The inside of the sideplate should also be numbered to the gun. The number on the yoke is an assembly number and should also be on the left side of the grip frame. The back of the right grip panel may also be numbered. Yours sounds early and should be marked "GHS" on the left side of the frame, behind the top of the cylinder.
Colt placed their serial numbers in the frame cut under the barrel. The number on their butt was a separate Army number. I assume yours is a S&W.