The Meaning of the Article and its Events
Burnet, Colden and Alexander engaged in an activity that was not new to science. It was fairly unique however, and according to a review of the articles published in Philosophical Transactions about similar activities, most of the other techniques were more commonly engaged in by astronomers. The bulk of the astronomy at this time dealt with popular observations involving the Earth, Sun and Moon, such as solar and lunar eclipses, along with more unique events like comet and asteroid discoveries.
Measurements involving the four moons of Jupiter and the five moons of Saturn then known to exist were perhaps not as rare and unique as the bulk of many of the activities being published, but this process was a great deal more useful to mathematicians, surveyors and engineers who knew how to make use of these planetary cycles and events. The “satellites” (as researchers referred to moons from other planets them) were often measured with other features in the background or tangential and proximal to them in order to make detailed measurements that were sometimes difficult to produce otherwise. Take for example the exact location of an object on the earth’s surface. The standard ways in which navigators engaged in this type of measurement were often pretty standard for the time, but did managed to have some chances for errors creeping into the calculation process. Major differences in the earth surface relative to true north and magnetic north, with local anomalies always at risk for happening, was the primary problem mathematicians had to deal with.
Whereas ship navigators tended to focus on the stars and planets as seen from typical hand-held equipment, mathematicians like Colden and others had the advantage of having a fairly large piece of equipment immediately available to them, and the stillness of the earth’s land surface (compared with water). This provided them with the opportunity to pay closer attention to the minutia of what they were observing, and play closer attention to the details of these objects such as moons cyclically traversing a planet’s surface, observations typically not focused upon while on board shipping vessels.
It was the cyclic revolution of the satellites about the planet Jupiter attracted astronomers interested in time measurements. Whereas the lunar events for the earth and the earth’s moon Luna were about 28 days in length, satellite activities involving Jupiters moons occurred more frequently and could often be measured and remeasured as part of the same observation period. The usefullness in using Jupiter’s moons to make measurements was the exceptionally short period time for some of these cycles. With knowledge of a number of important astronomical measurements, equations could be used to define where you were in the solar system relative to the planets being reviewed, which in turn could be related to the satellite activities of that planet.
For each of these happenings in the stars and planets, there were certain known measurements that were expected at certain places on the earth. This information was already fairly well tabulated, with the Greenwich line established by now to serve as the standard for most measurements to be calculated elsewhere in the world. A number of tables were also produced detailing the changes in earth magnetism relative to specific locations on the planet, and how this influenced the compass readings taken as part of each of the calculation processes. Since that part of New York which was being measured did not rest on an exact degree line, either in terms of latitude or longitude, the exact location of the Fort was calculated based on how the planets and their satellites aligned relative to Jupiter, the sun and the earth’s surface. This measurement could be repeated and compared with others due to the rapid movement of at least one of Jupiter’s satellite along it track.
Just how much of this activity served a realistic purpose and how much of it was engaged in to demonstrate the local science skills available within the local community is uncertain. But the fact is, it was done, and the method of calculation and result published in the Philosophical Transactions. This activity also demonstrated the great respect and attention paid to something Newton’s laws had helped to demonstate ample proof for. There was periodicity of events in the universe and the solar system behaved according to expectations. This perfect behavior of the universe was viewed with fascinations by scientists and the Deitists, as they were often called, but also equally appreciated and respected in awe by most theologians.
This dual point of view of the cosmos resulted in two arguments expressed regarding the presence of an orderly and predictable universe. First, this argument enabled Astro-theologians to develop their own theories about why these events were so predictable, and seemingly “perfect” in form and activities. Secondly, it enabled regular astronomers to rely upon other non-theological theories to define these predictable events. Both groups continued to write about this and published informative books on their various theories, for and against past and present religious teachings.
It is sometimes difficult to determine where colonial scientists such as Burnet, Colden and Alexander stood in this natural philosophy-natural theology conflict. Burnet seems to be more theologic in his activities and reasons for the events he participates in than Colden. The same seems to be true as well for Alexander.
The following is an Astro-theological take on the cyclicity and patterns which these three relied upon for their endeavor. This is followed by a Religious Writer’s citation of French Astronomer Msr. Giovanni Domenico Cassini (1625-1712), a scientist who popularized this method of carrying out measurements based on earth, sun and planetary movements and rotations and producing an ephemeris (schedule) detailing the movements of Jupiter’s satellites.
The following two scientific writings provide a historical background on this astronomical practice. The first is a review of the history of the methodology used by Burnet and others involving Jupiter’s moons. The second is a comment made by physician and scientist Fontanelle in 1699 about the value of such endeavors.