text: Besides his role in the determination of the figure of the Earth and his pioneering reports on platinum, Ulloa is also remembered in science for his description of the meteorological phenomenon known as "Ulloas halo", or sometimes "Bouguers halo", which an observer may see infrequently in fog when the sun breaks through (for example, on a mountain).  This is a fog bow, as opposed to a rainbow. A fog-bow is defined as "an infrequently observed meteorological phenomenon; a faint white, circular arc or complete ring of light that has a radius of 39 degrees and is centered on the antisolar point. When observed, it is usually in the form of a separate outer ring around an anticorona."
  The confidential report to the Marquess of Ensenada, signed jointly by Jorge Juan and Antonio de Ulloa and written around 1746, remained unknown to the public until it was published in London in 1826 by an Englishman named David Barry, under the title Noticias secretas de América ("Secret News from America"). Barry had spent some time in the newly independent Spanish America seeking opportunities for investment, only to become thoroughly disillusioned about the prospects for the region.  The Noticias secretas paints a dire picture of the state of the administration of the Spanish dominions in America in the 1730s and 1740s, alleging many instances of official corruption and mismanagement by both the civil and the ecclesiastical authorities, and denouncing the exploitation of the Native American population by unscrupulous governors and priests.  As such, it has caused enduring controversy among historians of Spanish America.