▁of ▁the ▁society , ▁through ▁ 1 9 5 7 ▁( host ed ▁by ▁Harvard ▁University ) ▁ ▁Death ▁of ▁Jason ▁Franklin ▁Ch ase ▁▁ ▁D w ight ▁Str ong , ▁Watch ▁and ▁Ward ▁Society ▁leader , ▁dies ▁ ▁New ▁England ▁Society ▁for ▁the ▁Supp ression ▁of ▁Vice ▁and ▁Watch ▁and ▁Ward ▁Society ▁annual ▁reports ▁from ▁ 1 8 7 8 - 1 9 5 1 ▁are ▁available ▁at ▁the ▁N ort he astern ▁University ▁L ibr aries , ▁Archives ▁and ▁Special ▁Col lections ▁Department ▁ ▁Category : C ensor ship ▁in ▁the ▁United ▁States ▁Category : Pol it ical ▁advoc acy ▁groups ▁in ▁the ▁United ▁States ▁Category : Organ izations ▁established ▁in ▁ 1 8 7 8 ▁Category : Organ izations ▁based ▁in ▁Boston <0x0A> </s> ▁The ▁standard ▁solar ▁model ▁( SS M ) ▁is ▁a ▁mathematical ▁treatment ▁of ▁the ▁Sun ▁as ▁a ▁spher ical ▁ball ▁of ▁gas ▁( in ▁varying ▁states ▁of ▁ion isation , ▁with ▁the ▁hydro gen ▁in ▁the ▁deep ▁interior ▁being ▁a ▁completely ▁ion ised ▁pl asma ). ▁This ▁model , ▁techn ically ▁the ▁spher ically ▁symmetric ▁quasi - static ▁model ▁of ▁a ▁star , ▁has ▁stell ar ▁structure ▁described ▁by ▁several ▁differential ▁equations ▁derived ▁from ▁basic ▁physical ▁principles . ▁The ▁model ▁is ▁const rained ▁by ▁boundary ▁conditions , ▁namely ▁the ▁lum inos ity , ▁radius , ▁age ▁and ▁composition ▁of ▁the ▁Sun , ▁which ▁are ▁well ▁determined . ▁The ▁age ▁of ▁the ▁Sun ▁cannot ▁be ▁measured ▁directly ; ▁one ▁way ▁to ▁estimate ▁it ▁is ▁from ▁the ▁age