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  • Writer's pictureEvan Boxer-Cook

Sundials for the Era of Timezones

Updated: Oct 5, 2023

Do heliochronometers enhance or limit the intuitive understanding of the celestial sphere?

Most extant sundials today were built for a time before modern timekeeping convention. That is, they were built to indicate local apparent time, not mean time at a foreign meridian.

Heliochronometers have existed for quite some time now, offloading the need for mental calculation of the equation of time–and later the longitude correction. This service is incredibly helpful, allowing the dial to be read at face value much like a clock.

As a result of this ease, however, it may be called into question whether these dials ultimately obscure the very movements they measure, atrophying illuminating knowledge of the celestial sphere and our world. If a dial is made to account for the EoT and longitude correction, the average operator is under no obligation (unless self-imposed) to understand how the dial functions.

From the perspective of a romantic sundial user, this may seem completely fine, even preferable, as the lower conceptual burden results in increased accessibility and more sundials in people's pockets. With the rather high bar to entry–understanding the relationship between time zones, longitude, and the rotation of the earth–eliminated, people interested in the notion of using a sundial can simply pick one up begin to use it reliably. They aren't required to understand how it functions, simply that it does.

Despite the enticingly romantic notion of sundials becoming commonplace timepieces, this vision is not the ultimate goal. Rather, is an increased awareness of nature's movements as facilitated by the sundial, a process which is fundamentally based on an ever-expanding understanding of process.

There will, of course, always be those driven individuals who, even when presented with a heliochronometer, will want to understand exactly why it works. For them, these types of dials are just as valuable and educational catalysts as any for a universal perspective. But for anyone less driven, heliochronometers may represent a premature wall. For those without a drive to understand, the ownership of this dial will satisfy their need and they will look no further into the science that lies beneath the surface.

The process of understanding the necessity of the equation of time and longitude correction is extremely valuable, prompting one to think about concepts fundamental to the movement of our planet. Understanding earth's tilting axis and elliptical orbit channel into an understanding of the equation of time; without the request of the instrument for its user to conceptualize it in a wider cosmic sense, the dial is conceptualized in isolation, it's educational potential squandered.

Plight of the Purist: effort over convenience

Despite the potential conceptual loss posed by the heliochronometer's use by the initiate, it is an incredibly useful convenience that deserves to be recognized for its practicality. Convenient technologies cannot simply be shut down when they become dissatisfyingly distanced from their fundamentals; innovation would cease to exist otherwise. However, when faced with such a product, it remains important to keep the process from being overshadowed by the outcome.

Just as algebra is still taught despite the existence of electronic calculators, the fundamental understanding of sundials on a universal stage must be preserved. For those well versed in the fundamentals of sundials and celestial motion, I see little wrong with using these shortcuts. For those decidedly uninterested or without the time for deeper thought–i.e. those walking through a park wanting only to look at something and know the time–heliochronometers are again an excellent choice. For the entry level sundial user, though, I believe it is best to withhold this convenience until a more comprehensive understanding is reached; or at least make sure the user understands how the automatic corrections of the heliochronometer are achieved.

It is worth noting the the mere existence of the heliochronometer may dissuade certain individuals from beginning their foray into this field of study. Consider the second type of consumer in the previous paragraph. If one's first encounter with a sundial allows them to read perfect time, they may not ever think to revisit the subject. This is impossible to avoid as long as the heliochronometer exists, and yet is not reason enough to discard them.

As stated previously, the heliochronometer is an invaluable convenience for many. It deserves to be used freely, but care must be taken to ensure that it does not blot out other dials which require cerebral and roundabout thinking in order to function; for it is this type of conceptual thinking that spurs contemplation and true understanding.

The Icarus

The duality explored in this article is perhaps best exemplified by the Icarus sundial, produced by Helios Sundials.

This portable dial is capable of displaying civil time for any timezone on earth, resulting from an accounting for both longitude and the equation of time. When compared to the equatorial ring dial, it presents a moderately less intuitive model of the celestial sphere, though easily surpassess it in terms of utilitarian value. Does the equatorial ring dial still have a place in our pockets if it is so outclassed? The answer, of course, is yes.

Just as sundials should not be seen solely as obsolete predecessors to modern timepieces, the OERD has intrinsic value to match that of the Icarus, due to its intuitive modeling of the celestial sphere and encouragement of the user to understand more deeply the equation of time and longitude correction. As with all sundials, the choice is deeply personal. The key is to make sure users are aware of this choice and perhaps more importantly, aware of what exactly–conceptually–the heliochronometer is doing when it accounts for these things.

To preserve societally and to continue pursuing personally a connection with the universe and a sense of worldly perspective, it is necessary to teach and remember the ways in which these corrections could be figured out manually if not for the convenience of the heliochronometer. This combats generation loss; allowing space for convenience while prioritising the natural, grounding, insighted existence catalyzed by sundial use.

Evan Boxer-Cook


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