1. Keep the lid sealed tightly at all times. Changes in the humidity within the jar change the sensitivity of the electroscope.

2. The cork should be snugly fit. It must electrically insulate the central rod and also be reasonably air-tight (for the reason stated above.)

3. Always use the same objects to charge the electroscope.

4. For long term observations it is best to take your data readings at the same location and at the same time every day.

1. Fully discharge the electroscope by grounding it with your hand.
2. Using a charged rod¹ fully charge the electroscope by contact.
3. The instant the charging rod is removed, start the stop watch.
4. Monitor the gradual discharge of the electroscope.
5. Stop the watch when you have determined that the electroscope is discharged.

   

6. Record the time required for cosmic rays to discharge the electroscope.
7. Make several data-collecting runs and average your results.
8. Record your data in a table and plot a graph of the results².

   Graph template for hourly observations
   Graph template for daily observations
   Graph template for weekly observations
   

¹ An ebonite or polyethylene plastic rod, when rubbed with a piece of natural fur provides an excellent source of electrons with which to charge the electroscope.
² The cosmic ray intensity can occasionally show large regional differences but in general their intensity varies on a global scale.