Dr Erich Schleier has kindly confirmed the attribution on studying the work in the original.
The drawing is connected to one of eight sections of the dome of the Gesù Nuovo, Naples, painted by Lanfranco in 1634-5 but destroyed in the earthquake of 1688. Other drawings showing the distinctive curving ribs of the dome are in the Uffizi and at Capodimonte (E. Schleier, Giovanni Lanfranco, un pittore barocco tra Parma, Roma e Napoli, exhib. cat., Parma, Reggia di Colorno, and elsewhere, 2001, nos. D35-36). The sheet at Capodimonte has the same watermark as the present drawing. Bellori describes the sections of the dome as being composed in two registers, for which the present drawing represents the lower half.