Vicente Tofiño's Atlas Marítimo de España and its Derrotero (1787-1789)
A survey of Spain's coasts built, on the certifying board's own account, as one unbroken chain of astronomical and geometric operations — sextant latitudes taken by several observers at once and separately, theodolite bearings from fixed points ashore, and chronometer longitudes cross-checked against eclipses of Jupiter's satellites observed at Paris at the same instant. Its stated purpose, quoted here from the 1787 derrotero, was that navigators everywhere should run fewer risks.
Why this wins its question: English accounts of Tofiño, where they exist at all, say that a Spanish officer charted Spain's coasts in the 1780s and stop. What made the atlas a scientific event was the method, and the method is described here from the certifying board's own dictamen at the front of the 1787 derrotero: simultaneous and separate sextant latitudes, theodolite bearings from fixed points ashore, chronometer longitudes cross-checked against Jovian satellite eclipses observed at Paris at the same instant, and the error distributed between verifications. The same object prints, from the same book, that the ministry's motives were commerce and war together, and that the working diaries were deliberately not published — so the reader can see exactly how far the printed evidence goes.
Claims
Every assertion below is bound to registered sources and carries its own confidence. Weight them; do not treat the page as uniformly authoritative.
The Derrotero de las costas de España en el Mediterraneo, y su correspondiente de Africa was printed at Madrid by the widow of Ibarra, her sons and company, "de órden superior", in 1787, as the book of sailing directions "para inteligencia y uso de las cartas esféricas" that accompanied the charts. Its title page names the charts as presented to the king by Antonio Valdés, Secretario de Estado y del Despacho Universal de Marina, and built by order of the king by Vicente Tofiño de San Miguel, brigadier of the Real Armada.
Tofiño's own titles on that page place the survey inside the naval teaching establishment and inside the European learned networks at once: Director de las Compañías de Guardias Marinas, member of the Real Academia de la Historia, corresponding member of the Académie des Sciences of Paris, socio literato of the Sociedad Bascongada and member of merit of the Amigos del País of Palma.
The charts and the derrotero were not published on the author's word. A Junta de Generales was convened by order of the king expressly to examine them, and its dictamen is printed at the front of the book; the claims about the survey's accuracy in this object come from that examining board rather than from the author's own introduction.
The dictamen describes the method it verified. Having compared the charts against the derrotero and the working diaries that produced them, the board found the work carried out by "una serie no interrumpida de operaciones Astronómicas y Geométricas": latitudes observed by several people and with excellent sextants, "á un tiempo y separadamente"; the trend of the coast and its bearings taken scrupulously with different theodolites at fixed points, or with good azimuth compasses at sea; and longitudes obtained with well-tried clocks whose rate had been verified repeatedly, the residual error being small and distributed between the observed points from one verification to the next.
The longitudes were checked by a second and independent method. In many places they were determined from eclipses of the first and second satellites of Jupiter, with the corresponding observations secured at Paris at the same moment; the board reasoned that the agreement of that result with what the timekeepers gave, the two methods being wholly independent, was "prueba incontestable" of the longitudes inferred from the clocks alone.
The board also stated what the survey was for, and the statement is not a national one only. The fixing of the coasts' positions, their trend, ports, coves, bays, watering places, shoals, sandbanks and rocks, with the transit lines by which to avoid them, was work "tan laudable como útil á la Nacion en particular, y en general á toda la humanidad", and those who had done it deserved universal recognition and imitation "para que los navegantes tengan en todo el orbe menos riesgos".
The introduction gives the motive of the ministry that paid for it without disguising the mixture. The growth of the Real Armada under the sovereign and "las oportunidades de la paz que vuelve las miras á la proteccion del Comercio, proporcionándose tambien ventajas sólidas para la dura necesidad de la Guerra" had inclined the Ministerio de Marina to take up every measure needed to make the branches of the navy flourish; the hydrographic atlas was preferred among them because of "lo grosero de los errores de los antiguos" and the profits expected from its exactness. Commercial protection and war are named in the same sentence as the reasons.
The published derrotero is explicitly a substitute for the primary record rather than the record itself. The introduction states that the instruction, divided in two parts, is meant to serve both the description of the merit of the work and the account of the means and precautions used, and thereby "excusar la publicacion de unos diarios" whose necessary prolixity could not escape being tedious. The observation diaries the board says it compared are therefore not in this book, and none of the numerical results is independently checked here.
This object rests on one printed source, the 1787 Mediterranean derrotero, and its claims about accuracy come from a board convened by the ministry that commissioned the survey — an official examination, not an outside one. No claim is made here about the dates or extent of the field campaigns, about the Atlantic and Cantabrian volumes of the atlas, or about how Tofiño's positions compare with modern values; nothing opened for this entry supports such a comparison.