 The revival of the observatory on the Gregorian Tower was initiated by the <unk> Francesco <unk> with the approval of Pope Leo XIII . High quality instruments were procured , partly with generous donations from <unk> of London , and the automatic recording instruments were procured from Richard in Paris . A four @-@ inch equatorial , a three @-@ inch transit instrument , and four <unk> clocks with two <unk> , were also procured from the observatory at <unk> . In 1888 , the gift of a 16 inch long telescope to Pope Leo XIII , became a part of the observatory . Father <unk> joined the observatory in 1889 after it was upgraded with more modern instruments . The same year , a second tower was built some 400 metres ( 1 @,@ 300 ft ) away from the main Gregorian Tower , overlooking the Vatican Gardens behind St. Peter 's Basilica on the south @-@ west border . It was built to a diameter of 17 metres ( 56 ft ) with a lower wall thickness of 4 @.@ 5 metres ( 15 ft ) , which could bear the load of a 13 inch photographic <unk> , newly procured from Paris . <unk> Father Rodriguez was the expert meteorologist who held the post of director from 1898 to 1905 . In 1891 , Pope Leo XIII , <unk> the <unk> <unk> <unk> <unk> , designated the second tower as the seat of the newly established Vatican Observatory , a decision which required altering the roof to provide a flat terrace for astronomical observations . 
