My Dear Castelli, It is my hope that you are fairing well and progressing favorably with your works on hydrodynamics.
As for me, I feel that I have come to the end of my life’s journey and I reckon that I have at the most a couple of days before my life is over. I therefore wish to share with you, my beloved student and colleague, some thoughts on my discoveries and experiments which I have involved myself in over the years. While I have had many inventions in my time, I concede that my discovery of the use of the pendulum for the measurement of time is the most significant one and while this blindness that afflicted me has prevented me from seeing my work to completion, I believe that my ideas will be utilized by others. As you my friend are aware of, I have dedicated many years of my life in analyzing the motion of the pendulum. I first proposed the use of the pendulum to keep time while I was trying to solve the longitude problem that had been advanced by his excellence King Phillip III. My thesis was that by use of the pendulum regulated clock, the hours, minutes and seconds that have elapsed since noon could be established. Through many experiments, I have come up with a number of claims about pendulum motion which I believe will be consequential for the use of pendulums in time keeping. All of my discoveries have been made not only by observation but also by mathematics since I am firm believer that mathematical reasoning should be used to establish conclusions in physics (Matthews, 2000).
My idea for a clock is to attach a stylus to a solid pendulum and each time the pendulum passes the vertical, the stylus should strike an elastic bristle fixed at one end and resting in the tooth of a horizontal crown wheel. This would result in the movement of the crown wheel forward one wheel therefore acting as a counting device. As of the present, I have invented the dead-beat form of the pinwheel escapement and although the importance of this invention is not obvious today, I harbor strong suspicions that it will someday be the basis for an accurate mechanical clock (Matthews, 2000). I am confident that in the near future, the pendulum will be the mechanism used for time machines and I have no doubt that it will replace the water clock and sundials. However, I do concede that the water clock has been one of the greatest aids in my scientific experiments. In my calculations of the speed of falling objects, the water clock provided me with the means through which I could accurately time the fall of objects from different heights (Hopwood, 1947). By use of my water clock, I have conclusively shown that some of Aristotle’s mechanics are greatly flawed.
While the great Aristotle proposed that different bodies fell at different rates, it is not obvious that all body fall at the same rate. My experiments have been in a bid to find a law which governs the increase that is exhibited by bodies as they fall. My inclined-plane experiments for relating time of fall to distance travelled have been most success. For the measurement of time, I employed a large vessel of water which I placed at an elevated position. At the bottom of the vessel, there was placed a pipe of small diameter which gave a thin jet of water which was collected in a small glass (Gilbert & Smith, 1997). The water collected was weighted after each descent therefore providing the basis for my time keeping. By use of the water clock, I could compare the time that the object took to travel each distance (Nova, 2010). I must pay homage to Doctor Santorio whose usage of the pendulum in the medical field was a breakthrough and heightened my interest in researching the various properties of the pendulum.
Dr. Santorio adapted the pendulum to enable medical practitioners measure a person’s pulse rate (Mulcahy, 1997). As you may recall, during the 1960s, Dr. Santorio used the pendulum to enable him to compare the pulse beats of patients within a certain period of time. He did this by building a pendulum and synchronizing its movements to the pulse beat of a patient by increasing or decreasing the length of the pendulum. A comparison of the patients pulse beat could then be made over a period of time to gauge recovery. I believe that this application of the pendulum is just but a tip in the iceberg of the potential that this instrument holds. While it pains me that I will not live to complete my lifelong dream of inventing an accurate time machine or even see the ideas implemented by another person, I am satisfied with the role that I have played in this revolutionary discovery and I am certain that history will remember me for my contribution.
Through the careful documentation of my ideas, I hope that others will pick up from where I have left off and come up with an accurate mechanical clock that will ideally revolutionalize timekeeping forever. I have no doubt that my invention will in future enable major advances to be made in astronomy, mechanics and other sciences for the good of humanity.
Gilbert, H. & Smith, D.G. (1997). Gravity, the glue of the universe: history and activities.
Libraries Unlimited. Hopwood, J. J. (1947). The growth of physical science. CUP Archive. Matthews, R. M.
(2000). Time for science education: how teaching the history and philosophy of pendulum motion can contribute to science literacy. Springer. Mulcahy, R. (1997). Medical Technology: Inventing the Instruments.
The Oliver Press, Inc. Nova (2010). Galileo’s Battle for the Heavens. Retrieved from: http://www.pbs.org/wgbh/nova/galileo/expe_inpl_2.html.