Prior to modeling software, architects needed a way to determine how the passing of the sun would affect houses they were working on. Are some parts of the house getting too much sun or not enough sun? Are weird shadows being created? Does the design work as well in summer, when the sun is higher, as in winter, when the sun's arc is lower?
To determine these answers, they needed two things:
1) An intern, to build the model and get everyone coffee to drink during the evaluation phase, and
2) A heliodon.
A heliodon was a big-ass contraption that a woman named Candace had to wheel into a room and set up.
There was a dial Candace could use to set the house's latitude.
Candace used this dial to set the month.
The varying rings corresponded with the sun's position in different seasons.
There was no motor. To move the sun from dawn to dusk over the model of the house, Candace had to put some elbow grease into it.
Here's what the process looks like on video:
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It should be noted that not all architecture firms had the heliodon operated by a woman named Candace; some firms went with a Victoria or Rebecca, and occasionally guys named Don, Peter or Thaddeus were allowed to touch it too.