"allowed him to observe" is a grammatically correct and commonly used phrase in written English.
It is usually used when describing how something enabled or permitted someone to watch or closely examine something. Example: The high-powered telescope allowed him to observe the distant galaxies in great detail.
Growing up as a Christian allowed him to observe his world more clearly, he wrote.
She feared for his life but allowed him to observe the battle from a distance.
When asked in 1968 to address a Congress of the Soviet Writers' Union, with Brezhnev present, he denounced the abhorrent abuses of human rights they had carelessly allowed him to observe and record.
He was particularly fascinated by marine life, and he developed underwater cameras and high-magnification lenses that allowed him to observe creatures like sea urchins, jellyfish and mollusks in their natural habitats, doing what comes naturally.
Mr. Johnson said that was when he first noticed a similarity between politics and sports, a venue that he said had allowed him to observe the good and bad in 28 other cities.
In the new book, he recalls his "only extended meeting with John Updike," in the late nineteen-eighties, which allowed him to observe "those busy eyes of his, the set of the mouth (as if containing, with difficulty, a vast and mysterious euphoria), his turban-shaped hair still forcefully thriving, his hands on the tea tray so much firmer than my own".
During this period he also invented devices for tissue grafting, allowing him to observe the effect of embryonic tissue transplants.
Eventually, he anticipates, they'll become so accustomed to his presence as to ignore him, thus allowing him to observe their authentic natural behaviour.
A Pakistani trainer stands on a walkway above the roofless rooms that allows him to observe and grade the troops' performance.
His new exhibition, titled You're Only Young Twice, is a series of portraits done before, during and after operations, after he persuaded surgeons in London and Philadelphia to allow him to observe their work.
His kinship with animals chimes with Rousseau's natural man; his outsider status and his scientific objectivity allow him to observe the decay of a great society without sinking along with it.
