Quaenam illae sint lineae per quas horae nocturnae digitorum adminiculo inquirantur?; Finger clock for determining the time at night; Fig. 18; p. 46; 1533; Petrus Apian: Horoscopion Apiani generale dignoscendis horis cuiusqumque generis aptissimum [...]. His accedit distantia[rum]; altitudinum; & profunditatum per idem hoc instrumentum dimetiendarum ratio longe accuratissima & ingeniosa [...]. [Ingolstadt]: [Apianus]; [1533]