For a large view, please click on the image.

A = revolving blades
B = stationary vanes
C = metal framework
D = copper jacket
E = Pulleys
F = Weights
G = Drum of wire
T = Hole for Thermometer

Image and explaination provided by: http://www.owlnet.rice.edu/~chem312/Handouts%20Folder/Joule_etc./
Joule.paddle.html

- Paddle Wheel Experiment -
 -                        1849                    -

This experiment involved the dropping of weights from a specific height; these weights would churn the water inside of the bucket and increase the overall temperature of the water slightly. This relationship served as the foundation to the First Law of Thermodynamics:

Image Provided by http://www.sciencemuseum.org.uk/galleryguide/E3011.asp.
Equation Provided by http://scienceworld.wolfram.com/physics/FirstLawofThermodynamics.html.