The pictures below are from two early machine made medicine bottles.I have put up pictures of the lips so that the readers can see how they mold goes all the way over the top as shown below. This is different than an older hand tooled, hand blown bottle.This style bottles curved bottom had several distinct advantages.First it forced the user to store the bottle on its side therefore keeping liquid in contact with the cork. The design was also much stronger than conventional flat bottom bottles so they were less likely to break from pressure, when used to contain carbonated water.I also speculate that another advantage to the round bottom is that once open the user was more apt to keep drinking since he could not easily rest the bottle without spilling the contents.These bottles are sometimes refereed to as Hamiltons.
One approach to helping beginner identify their old bottles involves show them the bases of old bottles.
the pontil is actually broken glass where the metal rod used to hold the bottle while the lip was form was broken off leaving a sharp scar.
Beginning collectors often confuse an Owen's ring with a pontil mark and it is easy to see why this happens.
This dating engine will estimate the age of your glass bottle based on its various attributes.
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