The use of electric light was a major step in the improvement of endoscopy. The first such lights were external although sufficiently capable of illumination to allow cystoscopy, hysteroscopy and sigmoidoscopy as well as examination of the nasal (and later thoracic) cavities as was being performed routinely in human patients by Sir Francis Cruise (using his own commercially available endoscope) by 1865 in the Mater Misericordiae Hospital in Dublin, Ireland. Later, smaller bulbs became available making internal light possible, for instance in a hysteroscope by Charles David in 1908.