# Could modern structural engineer be useful to medieval Master Mason?

I'm creating a world opposite of Les Visiteurs, where modern age structural engineer accidentally time travels to 13th century. When guards of the local lord arrest him on suspicion of being a spy, due to his weird clothing and the way he talks, he claims that he's mason from abroad looking for work. The lord is just starting a new castle and needs skilled workers, so he hires him but feels deeply suspicious of him, so he tells the Master Mason to keep an eye on the newcomer.

Would the Master Mason have any use of modern structural engineer knowledge or their level of technology is too low for any of it to be practical?

• @klingedion The question asks about a structural engineer in Medieval times not a master mason in modern times. – Bellerophon Oct 24 '16 at 21:21
• @Bellerophon Whoops, I got too excited about trying locate Les Visiteurs on Netflix and forgot to actually read the question. – kingledion Oct 24 '16 at 22:19
• Do you know anything about structural engineering? – JDługosz Oct 25 '16 at 0:53

Your structural engineer will have to have a very scientific mind - undoubtedly he has many skills which will be extremely useful, but he has to be able to convince his new colleagues of his theories.

Material strength, beam theory and formulae for the elasticity of materials had not yet been invented; these would allow for much more accurate calculations during construction. This would equate to great savings in terms of material cost; instead of throwing up all the superstructure possible to ensure a building is strong enough, they can now calculate the required strength and use only what is necessary, with a little factor of safety included.

Calculus had not yet been invented. This is one of an engineer's most important mathematical tools today, used to determine the forces in complex configurations of structural elements, shear strength of soil foundations, and lateral earth pressure and slope stability - all very useful for a castle which may be built atop a mound. Calculus is also useful for friction calculations.

Modern materials such as concrete could have been invented much sooner, as long as your engineer knows the correct properties and composition required.

But all of this relies on his ability to prove these mad ideas to his superior - whether through models and examples, or mathematical proofs.