At the time of Cottrell's invention, the theoretical basis for operation was not understood.

The Weibel was an advanced weapon at the time of its invention.

Around the time of the Mousers' invention, strange bank robberies were being held, with small tunnels leading into the vaults.

They were, I submit, even at the time of their invention, an overreaction to the circumstances.

Although the time and place of the dish's invention is unclear, it was well established in the American diet by the mid-19th century.

At the time of their invention, such devices were known as rectifiers.

Optical telescopes have been used in astronomical research since the time of their invention in the early 17th century.

There are over 200 tractors from the time of the tractor's invention and up until around 1970.

They were printed as persuasive religious material from the time of Gutenberg's invention.

The range of the fortepiano was about four octaves at the time of its invention and gradually increased.