The article is factually correct. Lemaitre proposed the formal mathematical idea but did no new measurements to test his hypothesis. Hubble made the first reliable measurements and discovered that the further the galaxy, the faster it appeared to recede. That was the first experimental evidence for an expanding cosmos, a feature that supported Lemaitre's hypothesis, vindicating his idea and the relationship that is called now "Hubble's Law". Hubble's new data verified the linear relaionship between distance and recession velocity.