Why did they do this?

[barnidoyll]

Found this boring bottle in the river the other day and wondered why they made them with this projection into the base of the bottle. It goes in about 1& half inches. The bottle is green, has 2 seams up to the base of the top. The top itself also has 2 seams but it must have been applied seperatly as the seams are on a different alignment . Anyway hope someone can help as i havent seen this particular question on the forums before. Thanks ....Brian.

 

[Roger]

Here is a previous discussion on kick ups https://www.antique-bottles.net/forum/m_9220/mpage_1/key_sediment/anchor/tm.htm

 

[barnidoyll]

Thanks Roger, never heard of a kick up before. I didnt realise a question could have so many answers....regards Brian.