The Cameron Heartometer
- Calibration from the Master Machine  -
Every Heartometer was adjusted by precision instruments to provide graphs similar in character and amplitude. Heartometers were checked against a mercury column with internal bellows movement measured and calibrated in 1/1000th of an inch increments.

A Heartometer in the process of final assembly in Chicago, being checked against the master instrument.  Company literature stated:

"Cameron Heartometers are most rigidly inspected, standardized and tested, checked and rechecked innumerable times against Master Devices to ensure accuracy.  It is vitally important that every instrument be as nearly identical to others of the same model in operation, actions and findings as possible."

Where is your Heartometer?  How is it displayed?  Please let us know!