**4. Conclusions**


for the braking bar) was well dimensioned. The *Hay inclined plane* was in operation from 1792 to 1944, and this fact corroborates all the results shown here. At the same time, the present research emphasizes that, from the point of view of mechanical design, the invention of William Reynolds has all the qualities to qualify it as a 'masterpiece'.

**Author Contributions:** Formal analysis, J.I.R.-S. and E.D.l.M.-D.l.F.; Funding acquisition, J.I.R.-S.; Investigation, J.I.R.-S. and E.D.l.M.-D.l.F.; Methodology, J.I.R.-S. and E.D.l.M.-D.l.F.; Project administration, J.I.R.-S.; Supervision, J.I.R.-S.; Validation, E.D.l.M.-D.l.F.; Visualization, J.I.R.-S.; Writing—original draft, J.I.R.-S. and E.D.l.M.-D.l.F.; Writing—review & editing, J.I.R.-S. and E.D.l.M.-D.l.F.

**Funding:** This research was funded by the Spanish Ministry of Economic Affairs and Competitiveness (MINECO), under the Spanish Plan of Scientific and Technical Research and Innovation (2013–2016) and European Fund Regional Development (EFRD) under grant number [HAR2015-63503-P].

**Acknowledgments:** We are very grateful to the Fundación Canaria Orotava de Historia de la Ciencia for permission to use the material of Project Betancourt available at their website. Also, we sincerely appreciate the work of the reviewers of this manuscript.

**Conflicts of Interest:** The authors declare no conflict of interest.
