San Francisco - 5 oz Class Type I, Large Font #, w/ Curved Stem Nines
This series represents the very first silver ingots produced by the Mint Of The United States At San Francisco; Type I oval hallmark, large font serial number, with curved stem nines in 999.75 fineness. This series is always stamped with the weight on the reverse and I have found the weight and OZS font to be consistent throughout the series even though the fineness changes. Exception to this is found only on the few heavier ingots ( +/-10 oz, +/-25 oz and +/-100 oz) within the numerical range of this series, where the OZS font size is larger. There is no consistent use of lot numbering in this series but Lot 195 shows up on a small range of serial numbers in the low to mid 200's. The numerical range of this series spans from just a few double digits to the low 1800's.
I can date this series back to the early 1930's through auction listing descriptions when resales began showing up and one specific donation to the American Numismatic Society from the late David M. Bullowa.
Type I oval hallmark, large font serial number, with curved stem nines in 999.75 fineness establish a standard size of 1.25 inches by 2.00 inches that is common through almost all other Type I ingots that follow. I have found both the height and width to be consistent with this standard, to within hundredths throughout.
This is one of only two series where a fineness change occurs, all other series are consistent throughout. The 999.75 fineness found on the early number ingots changes to 999.50 and then, 999.0 to finish the series. Along the way, 999.75 on at least three ingots was replaced with 999 3/4. Fractional values versus decimal point is not used on Mint Of The United States At San Francisco silver ingots; these three are the only ingots I am aware of that are marked this way.
The United States Government Silver Ingot Collection of Ken Conaway, Type I Oval Hallmark, Large Font Serial Number with Curved Stem Nines, includes every known variant in Registry.