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Navigation: The Method of the Marteloio (p. 47b)


Navigation: The Method of the Marteloio (p. 47b)


This is the second page of Michael's demonstration of the marteloio method for navigating "mentally." Here he uses the table to determine how to recover an intended course to the east after sailing 100 miles off course in a different direction. He calculates how far he would have to sail to get back to his intended course and how far he would have advanced toward his final destination when he did so.

See enlargement:

+ Ihesus + Poy volemo dir quanti mia seremo alargi dal ditto luogo. E vo- yando far la ditta raxion, prendi el chontrario de quel che tu à fatto e dirai che xe l'alargar de quarte due, sono 38/10, e lo rittorno e lo rittorno de quarte 9, che son 10 1/5, e mol- tipicha 38/10 fia 51/5, moltipicha e parti, insirà mia 38 38/50. E tanto seremo alargi dal ditto luogo. E per lo simille mo- do fara' ogn'altra raxion simille. E per voler archizar, zoè voltezar, saver tornar in cro- xe e veder l'avanzar arai fatto, e per lo simille de avanzar, chomo vedirì qui de sotto per singolo. E per esenpio la mia via sie per levantte e non de poso andar, e von mia 100 per la quarta de sirocho al'ostro. Quanti mia voyo andar ala quarta de griego alo levante che io vegna ala mia croxe, e quanto arò avanzado? Questo è lo muodo, che xe l'alargar de quarte 5, son 83/10, e lo ritorno de quarte 3, sono 18. Moltipicha 83/10 fia 18/1, fano 1494, e questi partidi per 10 serano mya 149 4/10, e tanti mya voio chaminar che sia ala croxe. E chi te domandasse che averemo avanzado, questo è lo muodo. Prendi l'avanzo di ritorno de quarte 3, che son 15, e l'alargar de quarte 5, che son 83/10, moltipichadi e par- tidi serano 124 5/10, e può azonzi l'avanzo del'alargar de quarte 5, sono 55, azonti fano mia 179 5/10. Tanto avra' avanzado. //

+ Jesus + Then we want to say how many miles we will be away from that place. And want- ing to make this calculation, do the opposite of what you have done and say that the distance off course of two quarters is 38/10, and the return of 9 quarters is 10 1/5, and mul- tiply 38/10 times 51/5, multiply and divide, will make 38 38/50 miles. And so we will be this far from that place. And by the same meth- od we will do all other calculations similarly. And if you want to tack, that is to turn, to know how to return to the course and see the advance you have made, it is done in the same way as the advance, as you will see systematically below. And for example, my course is to the east and I cannot go, and we go 100 miles southeast by south. How many miles do I want to go northeast by east so that I come to my course, and how much will I have advanced? This is the method, which is the distance off course of 5 quarters, which is 83/10, and the return of 3 quarters, which 18. Multiply 83/10 by 18/1, makes 1494, and this divided by 10 will be 149 4/10 miles, and this many miles we want to travel to our course. And if someone asks you how much we will have advanced, here is the way. Take the advance on the return of 3 quarters, which is 15, and the distance off course of 5 quarters, that is 83/10, multiplied and di- vided will be 124 5/10, and then add the advance on the distance off course of 5 quarters, which is 55, added makes 179 5/10 miles. You will have advanced that much.