Early 19th Century day or night telescope by renowned maker Thomas Harris & Son of London c1820. Two-draw brass telescope with mahogany barrel. Achromatic objective lens approximately 3.75 cm diameter. Protective sliding brass covers to eyepiece and objective lens. Brass has been cleaned but not polished to leave the telescope as original as possible. Engraved “Harris & Son London Day or Night” to first draw. Day or night telescopes were commonly used on board ship. As the name suggests, they could also be used at night because they had relatively large objective lenses to collect the maximum amount of light. Telescopes of this kind, marketed as “Day or Night,” were particularly valuable to watch officers stationed on deck at night. Closed length is 40 cm. Fully drawn length is 92 cm.
 
Thomas Harris originally established his firm in 1780 based at 9 and 22 Cornhill, London. He brought his son William into the firm in 1806 to form T Harris & Son – moving to 140 Fleet Street in the same year, and then 20 Duke Street in 1808. Between 1810 and 1817 they were based at 30 Hyde Park, but their main premises were at 52 Great Russell Street, occupying this address between 1816 and 1885. By 1890 they were at 32 Gracechurch Street, remaining there until 1901. The company had a royal appointment to the Prince Regent in 1819 and to King George IV in 1820. T Harris & Son were known as opticians and makers of globes, mathematical instruments, and telescopes.