This video features a discussion with Robert Crowitch (CBS Sunday Morning) to recall and explain Dolbear's Law, a scientific method for determining the ambient temperature based on the frequency of cricket chirps. The host, having forgotten the equation, is guided through the history and application of the formula: counting chirps over 15 seconds and adding 40 to yield the temperature in Fahrenheit. The video uses a güiro (a Caribbean instrument) to demonstrate the chirping sound and concludes by detailing the limitations of this "cricket thermometer," noting its inaccuracy when temperatures fall below 50°F or rise to stressful high levels.
Dolbear's Law: Using Cricket Chirps to Tell the Temperature
0:36 The Scientific Insect: The video introduces the concept that crickets can uncannily measure the outdoor temperature as accurately as a human thermometer.
1:12 Mimicking Chirps: For demonstration, the hosts use a güiro, a Caribbean percussion instrument, which closely mimics the chirping sound of a backyard cricket.
1:56 Origin of the Formula: The formula is known as Dolbear's Law, published in 1897 by physicist Amos Dolbear.
2:03 Dolbear's Law Defined: The simple formula is: Count the number of chirps the cricket makes in 15 seconds, then add the number 40. The result provides the accurate outdoor temperature in Fahrenheit.
2:43 Formula Demonstration: A musical segment demonstrates the counting process: 32 chirps in 15 seconds + 40 = 72°F.
3:26 Temperature Limitations: The accuracy of the cricket "thermometer" is limited because crickets are cold-blooded creatures.
3:43 Low-Temperature Limit: Crickets become sluggish and stop chirping at around 50°F, rendering the formula ineffective.
3:55 High-Temperature Limit: High temperatures (e.g., 95°F or higher) cause crickets to chirp at a furious and potentially unhealthy pace, making the count inaccurate or impossible.