▁long ▁in ▁obtain ing ▁ex quis it ely ▁defined ▁lun ar ▁pictures , ▁which ▁remained ▁un sur pass ed ▁until ▁the ▁appearance ▁of ▁the ▁Lewis ▁Morris ▁R uther f urd ▁photograph s ▁in ▁ 1 8 6 5 . ▁ ▁In ▁ 1 8 5 4 ▁he ▁turned ▁his ▁attention ▁to ▁solar ▁physics , ▁and ▁for ▁the ▁purpose ▁of ▁obtain ing ▁a ▁daily ▁phot ographic ▁representation ▁of ▁the ▁state ▁of ▁the ▁solar ▁surface ▁he ▁de vised ▁the ▁phot oh eli ograph , ▁described ▁in ▁his ▁report ▁to ▁the ▁British ▁Association , ▁On ▁Cel est ial ▁Phot ography ▁in ▁England ▁( 1 8 5 9 ), ▁and ▁in ▁his ▁Baker ian ▁L ect ure ▁( Ph il . ▁Trans . ▁vol . ▁cli i . ▁pp .   3 3 3 – 4 1 6 ). ▁Reg ular ▁work ▁with ▁this ▁instrument , ▁inaugur ated ▁at ▁K ew ▁by ▁De ▁La ▁R ue ▁in ▁ 1 8 5 8 , ▁was ▁carried ▁on ▁there ▁for ▁four teen ▁years ; ▁and ▁was ▁continued ▁at ▁the ▁Royal ▁Observ atory , ▁Green wich , ▁from ▁ 1 8 7 3 ▁to ▁ 1 8 8 2 . ▁The ▁results ▁obtained ▁in ▁the ▁years ▁ 1 8 6 2 – 1 8 6 6 ▁were ▁discussed ▁in ▁two ▁mem oir s , ▁entitled ▁Research es ▁on ▁Sol ar ▁Physics , ▁published ▁by ▁De ▁La ▁R ue , ▁in ▁conj unction ▁with ▁Professor ▁B alf our ▁Stewart ▁and ▁Mr ▁B ▁Lo ew y , ▁in ▁the ▁Phil . ▁Trans