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Natural Philosophy in the 1830s

By Neha Anil Kumar ’21

Class planning as a Princeton undergraduate today can be difficult to say the least. With a huge variety of distribution requirements I have to take, alongside the major requirements of a STEM concentration, the life of an AB Physics student can get quite busy. So, you can imagine my excitement when I found lecture notes for a class on “Natural Philosophy” taught by Joseh Henry in 1830s that covered topics on modern day physics, mechanical engineering, epistemology, and philosophy along with material science, belonging to a time when students’ classes were definitively decided ahead of time because each entering class was small enough to take all of its courses together.

As I dived right in, not knowing the vast array of topics I was going to be reeled into, I was caught by surprise just across the first two lectures of the series. Contrary to what I expected of an introductory science class, that I considered closely related to physics, the first few lectures delve into much more epistemology than I expected; though the structure of introduction does make intuitional sense. The series begins with an explanation of what science really is and its categorization into the physical (modern day natural science) and the metaphysical (modern day philosophy). Interestingly, to introduce science as a mix of philosophy and quantitative and experimental analysis of phenomena, there does occur a strange attribution of nature’s laws to “tendency of the human mind” alongside a descriptions of various laws simply attributed to divinity. For example, the term “law of nature” is defined as the human “conception of the mode in which Divine wisdom operates in producing the changes of nature.” Moreover, the physical aspect of science is further split into Somatology, defined as “constitution and properties of bodies,” and Mechanics, which deals with the static and dynamic physical systems, creating a blurry line between the physical laws that govern movement of bodies and the hypotheses surrounding the constituents of matter and atoms.

Somatology, today considered a branch of anthropology, was then defined as the constituents and properties of bodies. (Click to enlarge.)

The next seven to ten lectures seem to be a crash course on a wide variety of topics that one would cover in a mechanics class alongside an introductory atomic chemistry and materials class. Though the distribution of all the topics under each of the above subjects across the lectures may seem convoluted, the lectures still follow a logical flow by discussing atomic strictures and particles separately from mechanics, but drawing comparisons in each lecture to materials most commonly used and further discussing their properties. For example, after discussing the divisibility of matter and the porosity of substances, there is an extensive discussion on the appearance and porosity of specific minerals. Similarly, when explaining forces such as cohesion and adhesion, rather than an explanation of mathematical models of the force, there is much more discussion about the specific materials that provide the best adhesive quality and their real world applications.

The above is a diagram of a machine called the Attwood’s machine. A much more simplified diagram of the machine is still used today to explain forces! The precise and complex nature of the diagram Hamilton chooses to use, indicates the emphasis on understanding forces using real-world machines. (Click to enlarge.)


This coverage of a massive array of topics in a short span of time has its costs–in many cases physical laws that would be the center of most natural science classes today are not discussed in depth, with fewer mathematical models and explanations of why the forces exist and how they act in real world situations. This leads to the explanation of force, mass, and other concepts through machines that are directly applicable in the machines they probably used. What is particularly interesting is that the lack of mathematical models results in the compulsion to express physical laws as simple “apparent properties” of the bodies which might be conceptually confusing for a natural science student today, because of the addition of a more philosophical outlook. For example, when explaining the concept of rest, the characteristic is attributed to a physical law that is merely illusive, because in reality the Earth and everything around us is in constant motion. Whereas this analysis is true, it raises conceptual questions about “rest” rather than efficiently explaining the basis on kinematics through mathematics.

Here, a particular combination of foci and weights to form a lever is easily taught through the application of the lever in a real-world situation. (Click to enlarge.)

The next half of the lecture series discusses thermodynamics, buoyancy, friction, and  hydrodynamics, all under the context of the ability to harness different types of energy. In accordance with the pattern I had seen so far, there was very little lecture pace given to understanding mathematical models of force, power, and energy. Rather, there are detailed descriptions of various machines and instruments that are most commonly used today to measure aforementioned qualities like buoyancy and air-pressure, alongside machines that harness various types of energy to perform integral tasks of the time. This sections seems to be heavily application based, where students are being trained to understand machinery of the time to be able to use and improve it in the future, probably. Therefore, there is again very little concentration of the application of mathematical models of force and energy on simpler systems.

Diagram of a particular instrument used to measure air pressure. (Click to enlarge.)
The lectures spent a good amount of time also on the water bodies and rock formations that allow us to harness energy, a concept that would now likely be taught in a geology class. (Click to enlarge.)
There was also a discussion of harnessing energy from water, besides the more basic concept of a turbine. Discussions delved into more specific machines that are slightly more complicated but probably used often. (Click to enlarge.)

Therefore, reading these lecture notes suggests that defining this class on Natural philosophy as a class on specifically physics, chemistry, philosophy, or material science would be incorrect. What the class aims to teach is concepts on machines, materials and constituents of bodies directly applicable to circumstances around them by concentrating on explanation through machines and particularly useful materials.

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