glass

It is not clear up that oldest glass was developed.

These are past glasses.

Past glass is unique form.

This is glass used  in 13 century.

      

This glass used in18 century.

 

This is glass used in 19 century.

This is present glass.

present glass is very convenient.

Because it is not slipped down from nose. 

This is a future glass !

This glas load with computer.

We can read  web sites through this glass!