It plays a significant role in the story rather than being gratuitous, but for some of you, it may be upsetting and knowing this fact may not be enough.
For example, if the equation of time is -5 minutes and the standard time is 9:40, the sundial time is 9:35.
The original was published in 1965 under the title Les Cadrans solaires by Gauthier-Villars Montrouge, France.