JoK Street Lamps, according io the Lengths of ihc iSfigfils. \ 17 



iheir Lamp-Lighters, for such purposes, at short Intervals, and 

 in variable quantities, suited, as they imagine and allege, to the 

 different seasons of the year, as well as to the number of Lamps : 

 but of the suitableness of which adjustment, there is often room 

 to doubt, from the very frequent complaints, which Roards and 

 Vestries have occasion to make, of the Lamps going out, before 

 Morning, and the known frequency, of the Contractors, in such 

 case, charging the fault on their Lamp-lighters, who often arc 

 alleged, to have purloined a part of the Oil which had been servpfl 

 out to them; and from the almost equal frequency, of the Men 

 retorting, by alleging the quantity of Oil intrusted to them, to 

 have been insufficient for the number of Lamps and the lengths of 

 theNights, for which it was served-out: It appears therefore not 

 unreasonable to suppose, that more correct information on the 

 subject, might greatly lessen the numbers of these instances, of 

 defective lighting, and the consequent charges and counter- 

 charges of the blame, by the Contractors and their Servants. 



And towards supplying this information, the numbers of Hours 

 and Minutes, on each Night in the year, have been ascertained, 

 during which the Sun is invisible at London, because below the 

 horizon, after applying a due correction for Refraction, to the 

 time of Sun set and Sun rise, which is set down in tl)e Nautical 

 Almanack, independently of refraction ; and these times or lengths 

 of Nights, have been arranged in a Table, commencing with the 

 29th of September, (such being the day on which Lighting Coi.- 

 tracts most commonly commence) of a common or non-Bi>!sextiic 

 vear: and these, on being cast up, appear to amount, annuallv, 

 to 4259'' 42"'. This divided by 365, gives ll*" 40'"-22 for the 

 ;iiean length of Night, for which Lamp-ligliters contract; and 

 this last multiplied bv 7, gives their mean length of Week, equal 

 to81Ml'"-57. 



Bv long experience, or else by communicating with others in 

 the Trade, most Lamp Contractors are enabled, to calculate, 

 pretty accurately, the who\e annual q?ianlity of Oil, necessary 

 for the supply of each Lamp, of the kind and size which they 

 have in us.e; answering to the above stated 4259'' 42™; and if, 

 as is done above, this quantity of Oil (either in pounds, or in 

 pints, &c.) be divided by 365 and multiplied Ijy 7j the average 

 weekly quantity for each Lamp, will be obtained, and this multi- 

 plied by the number of Lamps, will show the quantity, that should 

 be served-out to each Lamp-lighter, on each of 52 day^ rc-.pcc- 

 tively, which will be found in Table I. sent herewith. 



Taklis 



