The Story of Tipped Bulbs
“The earliest light bulbs, or electric lamps as they were once referred to, had pointed projections called “tips” on the very top of the bowl of the bulbs, as seen on the accompanying photo. These tips are simply the solidified, pointed glass left by the removal of the exhaust tube which was used to pump the air from the inside of the bulb in the final process of sealing the bulb while the tip was still soft, molten glass.
“Sometimes, a tip may have a stylish-looking bead of glass accentuating it. This bead may have simply been the signature work of a dexterous glass blower flaunting his skills or it may have been placed there to reduce the tip’s chances of breaking. These are simply speculations.
“Although the tip of an old light bulb may look quite attractive and give a sense of nostalgia to the bulb collector, back in the days of tipped light bulbs both the manufacturers and purchasers of those bulbs were not quite so fond of them. A tip on a light bulb would cast a subtle yet very annoying shadow. Moreover, a tip was also the weakest point of the light bulb and thus would break quite easily if it were just simply bumped against, fracturing the bowl of the bulb and allowing air to enter whereupon the bulb would no longer function. Although tip-less bulbs were sometimes manufactured during the late 19th and early 20th centuries, they were quite expensive to produce and hence were not common. It wasn’t until 1919 when a new and inexpensive manufacturing method allowed the air to be pumped out from the base were tip-less light bulbs finally made obsolete.”