Lewis Patent Lamps and Spherical Reflectors
Winslow Lewis, a former ship captain from Wellfleet, Cape Cod, patented his version of the Argand Lamp on June 8, 1810 and sold his reflecting and magnifying lantern patent to United States Government just prior to the War of 1812.
Although the Lewis Patent Lamp required only half of the oil used by Spider Lamps, the intensity of his lamp was 400 times less that of the Argand Lamp used in Europe. Lewis promoted his device as a magnifying and reflector lantern claiming the system was a combined Lamp and magnifier with reflectors. In a effort to increase the lamps intensity, Lewis placed a lens, a magnifier made from a 4-inch diameter green bottle glass, in front of the flame to focus the straying beams of light. His magnifier accumulated soot immediately further dimming the Light and was later removed. Lewis lamps required constant adjustment and cleaning due to the inadequate draft and defective brass gears.
The design of his silvered plated copper reflectors was another reason why his Lewis Patent Lamp was less effective than the Argand Lamp. The reflectors silver finish was too thin to withstand abrasive cleaning and the thin copper could not hold its original parabolic shape when exposed to the heat of illumination. As a result, Lewis reflectors were altered into a spherical shape and the worn down reflective silver finish scarcely reflected the Lamps light. The spherical reflectors were inferior to the parabolic reflectors used behind Argand Lamps.
The Lewis Patent Lamp was basically a poorly modified version of the Argand Lamp and parabolic reflectors. As one inspector noted the magnifier made a bad light worse, yet Lewis did not argue with his critics. He used the economy of the Lamp emphasizing the 50% oil savings over the Argand Lamps.
In 1812, Congress approved the first contract for the maintenance of Lighthouses authorizing Secretary of the Treasury, Albert Gallatin, to purchase Winslow Lewis patent Lamps with Winslow Lewis refitting all Lighthouses in the United States with Lewis patent Lamps and to keep the new lantern system repaired.
There are different accounts* of how Winslow Lewis was able to install a inferior Lamp system in American Lighthouses. According to Federal Law, contracts were awarded to the Contractor with the lowest offer as noted by Stephen Pleasonton, Fifth Auditor of the Treasury Department and federal administrator of U.S. Lighthouses.
Winslow Lewis strongly promoted his own system of lighting and was frequently awarded contracts due to his low bids. In 1817, Winslow Lewis listed and described all American Lighthouses and noted his method of Lighting consumed 24,731 gallons of oil annually whereas the annual consumption of the prior oil Lamps was 52,000 gallons. A 52% fuel savings was most likely the major reason why a new developing nation approved the Lewis Lighting contract.
*There are sources that allege collusion between Winslow Lewis and the Fifth Auditor, Stephen Pleasonton yet these allegations were made 30 years after Winslow Lewis was awarded the Lamp contract. In 1842, his nephew, Isaiah William Penn Lewis (I.W.P. Lewis), claimed his uncles Lamp was copied from Europe and his reflectors were bad after Pleasonton refused to adjust contracts for I.W.P. Lewis bids. Winslow Lewis died on May 20, 1850, several years before the alleged relationship with Pleasonton was exposed to Congress.
Authors Note: The law mandating the acceptance of the lowest offer was either a blessing or a curse. Many Lighthouses were built to stand the test of time with diverse Architectural styles using aesthetic functional structures. Unfortunately, many Lighthouses were first built using poor construction and poor engineering practices resulting in a constant state of disrepair. In addition, this law was a reasonable way for a recently formed government to be cost effective.
Winslow Lewis became the main Lighthouse Contractor for 30 years after rebuilding Franks Island Lighthouse (July 1818- March 1823) despite some questionable work done on the original structure by his sub-contractors, Benjamin Beal and Duncan Thaxter (1). After the dilemma of Franks Island Lighthouse, Winslow Lewis formed an alliance with Stephen Pleasonton, the Fifth Auditor of the Treasury and U.S. Lighthouse administrator (1820-1852) by winning contracts to build Conical Brick Lighthouses cheaply. Winslow Lewis consistently submitted the lowest bids and there was no hard evidence of illegal dealings between Lewis and Pleasonton (2). Winslow Lewis ignorance of engineering caused most of his Lighthouses to be replaced by taller structurally sound structures.
Although his nephews allegations were incriminating and Lewis Patent Lamps were poorly designed and manufactured, research has yet to find evidence that he violated federal law. Stephen Pleasonton was given an administrative task that was outside his accounting knowledge. With no engineering background, Pleasonton awarded contracts to the lowest bidder per the law yet he was unable to verify the contractors qualifications. Congress later corrected these problems by creating a Board with experts from every trade involved in constructing Lighthouses.
For 40 years**, American Lighting technology did not improve due in part to the cost of expensive European Lighting and whether existing Towers were built to structurally support the additional weight of the lens (a First-order Fresnel lens assembly can weigh up to 3-tons and was priced at $12,000 shipped in 1841). In addition, Winslow Lewis lobbied successfully to protect his Lighting System.
In 1851, Congress ordered a investigation of the nations aids to navigation after receiving numerous strong complaints about the poor quality of Americas lighthouses, specifically the lights. Interestingly, Congress authorized two Fresnel lenses for testing in 1838 and the Navesink Twin Lights were refitted with First-order Fresnel lenses in 1841. Nine more years elapsed before the second Lighthouse was fitted with a Fresnel lens. After the successful tests, the Fresnel lens was not installed in the remaining Lighthouses until Pleasonton was replaced by he U.S. Light-House Board. Pleasonton insisted most keepers could not operate the new complex system and additional testing was required.
On October 9, 1852, Congress established a nine member Lighthouse Board in response to the investigation that uncovered the poor condition of American Lighthouses. The Board included two Army Engineer Corps officers, two Navy officers, two Topographical Engineers officers, two scientists, and the Secretary of the Treasury who served as President of the Board. This team of specialists acted immediately in using new technology and all Lighthouses were refitted with Fresnel lenses by the time of the Civil War.
The new lens system was three times the cost of the Lewis Lamp system yet the efficiency of the Fresnel lens assembly reduced fuel costs by 75% on average since only one oil lamp was needed whereas the Lewis system required many oil lamps. The major advantage of Fresnel Lenses was a 400% increase in the intensity of the focused beam of light over the Lewis Lamp system (Catoptric light). Eighty-three percent of the light is lost at the top and and bottom of a Catoptric light whereas a Fresnel catadioptric system collects and redirects 83% of the light into a focused horizontal beam.
** For 11 years (1812 to 1823), Lewis Patent Lamps were used instead of the superior Argand Lamps with parabolic reflectors. In 1823, the first lenticular apparatus or Fresnel lens was installed the Cordouan Lighthouse at the mouth of the Gironde River near Royan, France. American Lighthouses continued to be illuminated by Lewis Patent Lamps for another 29 years (1823 to 1852). Prior to 1852, Fresnel Lenses were tested at three American Lighthouses; Navesink Twin Lights (1841 - New Jersey), Sankaty Head Light (1850 - Nantucket, Mass), and Brandywine Shoal Light (1850 - Delaware). From 1852 to 1859, all Lighthouses in America were refitted with Fresnel Lenses.
(1) Benjamin Latrobes Designs for a Lighthouse at the Mouth of the Mississippi River by Michael W. Fazio
Special thanks to Jay Riedl, Lafayette, Louisiana, for his assistance in researching Franks Island Lighthouse.