[NJARC] connecting batteries in series

[victor bellini]

I am working on a project involving an old crosley transistor radio that my 
dad brought home when I was but 12 years old. It actually has tiny tubes in 
it (not mini's). It has two batteries including a 45 volt and a 4.2 volt 
mercury.
To my surprise, the 45 volt battery is still manufactured by Eveready but 
the 4.2 volt mercury is long out of production. I have learned that placing 
three AAA batteries in series is an acceptable 4.5 volt alternative but do 
not know how to connect the batteries. Soldering seems like a dangerous 
alternative. I am looking for suggestions on how to connect single cell 
batteries together. Thanks.