In the novel Death in the Clouds, Silas Harper is the name used by an American who went to Universal Airlines at 254 Boulevard des Capucines. Mr Harper offered Jules Perrot 5000 francs, to tell Elise Grandier that the 8.45 flight from Le Bourget to Croydon was fully booked. Silas Harper wished to be seated next to Madame Giselle at the 12 o'clock flight, so he could negotiate a loan from her, and he wished they the meaning would appear to have taken place by chance.
Silas Harper never showed up onboard Prometheus.
Mr Harper is described as “tall, stooped, had grey hair, horn-rimmed glasses and a little goatee beard”.