For example, the particular style of "star" on the base of the liquor bottle pictured to the left is widely acknowledged (in the collector world) to be a decorative marking of the San Francisco & Pacific Glass Works (SF&PGW - 1876-1902) since most of the bottles with this marking are either found in the West or are otherwise embossed with Western company and/or product names (Toulouse 1971; Zumwalt 1980).
This commonly encountered symbol (at least in bottles found on Western historic sites) was intended either as a cryptic form of makers mark or simply an artistic flare of a specific mold cutter or engraver at the SF&PGW (or located in the Bay Area).
Most significant here are markings related to the feeding of the glass to the mold - a subject covered later on this page in the "Machine-made bottles" section.: The bases of many bottles have embossing or symbols that pertain to the product that the bottle was designed to contain and/or the producer or bottler of the product.
Consult the IMACS website above if interested in the nomenclature of describing base profiles.Also, shape is extremely variable and usually only loosely connected with age and function.The bases of both mouth-blown and machine-made bottles have various features and/or makings which can greatly assist in determining or narrowing down the age of the bottle.However, the rectangular and square bottles also have distinctly beveled edges and the octagonal bottle is actual round right at the heel of the bottle - all of which complicate describing the base profiles a bit.The best readily available source for classifying bottle base shapes/profiles is the "Bottle Base Profiles" illustration that was previously included in the IMACS (Intermountain Antiquities Computer System) guide.