architect and builder of Gruber Palace — a vast rococo edifice that was originally his mansion — used for his research in physics and hydraulics. It had also an astronomic observatory. The palace was bought in 1887 by the Carniolan Savings Bank and has housed the Slovenian archives since 1965. Return to the Jesuits In 1785, Gruber went to Polotsk, a border city between the Polish–Lithuanian Commonwealth and the Russian Empire to rejoin the Society of Jesus and became a member of the Jesuit community in Russia. Gruber was an active engineer, chemist, architect, painter, mechanic and physician. Under his influence, the Jesuit College in Polatsk became a famous academy of technical science. He was influential in the court of Catherine the Great, and was close to her successor Tsar Paul I, at whose request he reorganized the technical training in the whole Russian empire. In 1800 Gruber became the first rector of the Aristocratic College at the Saint Petersburg State University. Superior General Living at Saint Petersburg, and being a close confidant of Paul I, Gruber often discussed with him the affairs of the Society, on behalf of Franciszek Kareu, Vicar General of the Jesuits in Russia. In 1797 he became officially the Assistant of Kareu and ultimately, after the death of the later, Gruber was elected Superior General of the Society of Jesus in Russia, at the Regional (Polotsk) Congregation IV (1802). That was just a few months after Pius VII had issued the brief Catholicae fidei (1801), giving approval to the existence of the Russian Jesuits and making the Temporary Vicar (Franciszek Kareu) 'Superior General for Russia'. Gruber expanded pioneering activities by opening several missions among the Germans in the Volga region (Saratov, 1803), Odessa (1804) and Astrakhan (1805) where schools and agricultural activities were developed. However, politically, problems were growing with Paul I as well as with the local bishop of Polatsk. Towards reunification In the meantime the movement towards reunion of the Jesuits was gaining momentum. In the wake of the French revolution political opposition of the Bourbon courts had weakened. In 1803 the Jesuits of Stonyhurst College in England were made members of the Russian Jesuit province. The 'Fathers of the Faith' an independent group of ex-jesuits received affiliation in 1805. Contacts were established with the ex-Jesuits of Maryland (USA). In 1804, the existence of the Jesuits was officially recognized in Naples and Gruber