There are, or were, two drawings in the sacristy or crypt of Rosslyn Chapel. On the right of the above image is a drawing of on of the pinnacles which surmounts one of the flying buttresses. The drawing is scratched on the south wall of the crypt (that is the wall on the right as one enters the crypt). The drawing cannot be identified as relating to any particular pinnacle as it appears to be a drawing which concentrates on the engineering aspects of the construction (e.g. load-bearing and thrust factors etc.). It is more likely that it is a general drawing of the pinnacles in which the final decoration is not included.

In the main part of the image there are several diverse parts.

A) This is a pointed arch in the retro-choir

B) This is a vaulting rib with cuspings and again almost certainly describing part of the retro-choir. The reason for being able to state this with certainty is that the number of cusps corresponds with the number of cusps for the vaulted ribs in the retro-choir.

C) On the far right a variety of lines which appears to refer to vaultings but they are either incomplete of have been partly erased so that they cannot be compared to any specific part of the chapel.

D) Two partial drawings both of circles one of which is cusped. The uncusped circle has insufficient detail to make any suggestion as to what it might represent. The cusped circle, it is though, represents the intended parapet of an aisle.

So why are these drawing here? Given that they show nothing of the actual decorative carving now in Rosslyn Chapel we can draw some tentative conclusions. These are almost certainly ‘engineering’ drawings designed to calculate and show the basic construction of the chapel. If true this means that the crypt was built before the chapel proper and may even mean that the date of 1446 refers to it rather than the building as now exists. It would also mean that the crypt was the design workshop where the stonemasons drew up their ‘blueprints’. Drawings such as these, on a vertical surface, are very rare and perhaps indicate specific and repetitive design elements that required to be regularly referred to throughout the design and building process. The weakness of this argument lies in the fact that there are a great many other, more important, parts of the chapel which would also require to be referred to regularly and would have merited a permanent drawing for the same reason. An alternative suggestion is that these drawing are simply trial drawings intended to resolve specific problems of construction.