Once the exact location of the target is known, it's latitude and longitude are fit into the apparatus by means of a perforated tape, which is concealed inside.
9 seconds sound clip from Superman (1948) - The Reducer Ray (Chapter 3).
You can hear this line at 00:07:56.418 in the Blu-ray version of the episode.
Quote context
[...]
- Superman, I'm very happy to know you.
- I see.
- Will you step over here, Superman?
- That is, if you're free to say.
- Why, I think it's safe to tell you. Dr. Graham, will you explain, please?
- The machine, from then on, makes its own calculations.
- Have all arrangements for the test been completed, doctor?
- A concrete block house has been built in the Western dessert, miles from any habitation.
[...]