July - 15 years ago; 60 years ago; 85 years ago; 205 years ago

15 years ago 

Nathaniel Wyeth died. From Pennsylvania, US, Wyeth is best known for developing the polyethylene-terephthalate (PET) drinks bottle. PET was the first plastic strong enough to hold pressurised carbonated drinks and safe enough to meet with the Food and Drug Administration’s approval. His 1973 patent for this was assigned to Du Pont.   

60 years ago 

On 16 July, the world’s first atomic bomb was exploded at the Trinity site in New Mexico, US. The fireball expanded to 600m in two seconds and grew to a height of more than 12km. The bomb’s explosive power, equivalent to 18.6 kilotons of TNT, was almost four times larger than predicted. The test was the culmination of the Manhattan project 

85 years ago 

Rosalind Franklin was born in London. Her x-ray diffraction photographs of the B form of DNA showed a double helix. In the 1950s Francis Crick and James Watson used these pictures to solve the DNA structure. Franklin never received the recognition she deserved for her work and died of cancer four years before Crick and Watson were awarded the Nobel prize.   

205 years ago 

Jean-Baptiste-Andr? Dumas was born in France. He isolated anthracene from coal tar and developed the vapour density method for determining atomic and molecular weights (Dumas method). In 1848 he moved into politics, becoming minister of agriculture in 1850 and the master of the mint in 1868.