Mendeleev's predicted elements
Dmitri Mendeleev published a periodic table of the chemical elements in 1869 based on properties that appeared with some regularity as he laid out the elements from lightest to heaviest. When Mendeleev proposed his periodic table, he noted gaps in the table and predicted that as-then-unknown elements existed with properties appropriate to fill those gaps. He named them eka-boron, eka-aluminium and eka-silicon with atomic masses 44, 68 and 72 respectively.
Edgar James Banks
Banks is credited with the discovery of the Plimpton 322 tablet in Southern Iraq. It is believed to be the world’s oldest trigonometric table, predating Hipparchus by around 1000 years and, using base 60, also the most accurate trigonometric table, avoiding inexact numbers. It thus displayed knowledge of the Pythagorean theorem long before the birth of Pythagoras himself. The ancient cuneiform tablet was sold to the New York publisher George Arthur Plimpton, reportedly for $10. It was housed in Plimpton's private collection before being donated to Columbia University upon Plimpton's death. The artifact, now famously known as Plimpton 322 (denoting that it is the 322nd item in the catalog), has provided great insight into the Babylonian era mathematics.