Venus, a "Pulquería", and an Observatory

People strolling around downtown Mexico City in 1875 might have come across countless “pulquerías” with odd names (pulque is a beverage made from the fermented sap of the maguey plant, Wikipedia dixit). But for weirdness of denomination none beat the latest addition to the long list of hangouts for the brothers in pulque: ”El tránsito de Venus.” The name was no allusion to Roman mythology, but the pulque fraternity´s way of celebrating a major scientific event that took place in 1874.

That was the year a Mexican expedition traveled to Japan to observe the transit of the planet Venus across the sun´s disk. Venus transits occur in pairs, the second transit in a pair coming eight years after the first. Consecutive pairs of transits happen at intervals of more than one hundred years. The transit of 1874 was the first in a pair, the previous one having taken place on June 3, 1769.

Venus transits are interesting because they allow scientists to measure “solar parallax” --a quantity from which the earth-sun distance can be accurately computed. The Mexican team was part of an international effort to determine solar parallax. Enthusiastic about the project, President Sebastián Lerdo de Tejada chose Francisco Díaz Covarrubias, a geographer from the Colegio de Minería, as head of the expedition. There were, at the time, no secure roads between Mexico City and the Pacific, so Díaz Covarrubias and his team took a train to Veracruz, stopping in Orizaba for several days after learning that an epidemic of black vomit was ravaging the port. From Veracruz they traveled to Havana and Philadelphia, then on to New York, where they inquired about ships leaving San Francisco for Japan. (No, I don´t know why they took such a roundabout route.) They then crossed the United States, arrived in San Francisco, and on October 19, sailed aboard the steamer Vasco de Gama. The Mexican expedition made landfall in Yokohama on November 9, 1874, precisely one month before the transit.

Díaz Covarrubias intended to build two observation stations on Japanese soil, but he needed permits. Unfortunately, they had reached Japan at the time of a national holiday, and Díaz Covarrubias had to wait for several days before he got an answer from the Japanese government. During this time he hired a Chinese carpenter who understood some English to assemble the stations. When the government finally responded, it did so handsomely. They even provided a special telegraph line for the Mexicans to communicate with their American and French counterparts, in Kobe and Nagasaki. The transit was duly observed on December 8-9, 1874.

Díaz Covarrubias and his men sailed home via the Indian Ocean, the Red Sea, the Suez canal, the Mediterranean, and Paris, where they published their results. They then crossed the Atlantic to Veracruz. On November 19, 1875, the train carrying the Mexican expedition rolled into the Buenavista station. The men were given a hero’s welcome, recounted the following day in the daily El siglo diecinueve .

I wonder if the event stirred the patrons of “El tránsito de Venus.” Did they discuss it? Did the pulquería take pride in making the news that day? Did a chorus of pulque-besotted voices toast the men who had sailed around the world to witness the event celebrated in their saloon´s strange name?

Whatever the reaction of the pulquería´s clients, the following year Porfirio Díaz, the new president (and future dictator), signed a decree whereby Mexico was officially given a National Observatory.