Cust demonstrating his Patent Rangefinder, circa 1904
Image information
Cust demonstrating his Patent Rangefinder, circa 1904
Cust's Patent Rangefinder (Museum object NAV1581) was designed to be mounted on an Officer of the Watch telescope or on a monocular. It works from knowing the height of a masthead, funnel or other feature of a ship, with the distance measured from the angle subtended by that feature. When placed in front of the telescope, two prisms in the rangefinder produce a double image, which is altered by revolving the front prism. When the double image is resolved into a single one, the angle is read off the graduated scale, which has a vernier allowing it to be read to an accuracy of 10 minutes. The angle can then be converted into a height using a slide rule that was supplied with the rangefinder. This example is inscribed with the name of the manufacturer and with its patent number (no. 15221). It is contained in a leather carrying case.
- Image reference: L3734-002
- National Maritime Museum, Greenwich, London
Discover more
More by this artist
Search for similar images
Product images of Cust demonstrating his Patent Rangefinder, circa 1904
Our prints
We use a 240gsm fine art paper and premium branded inks to create the perfect reproduction.
Our expertise and use of high-quality materials means that our print colours are independently verified to last between 100 and 200 years.
Read more about our fine art prints.
Manufactured in the UK
All products are printed in the UK, using the latest digital presses and a giclée printmaking process.
We only use premium branded inks, and colours are independently verified to last between 100 and 200 years.
Delivery & returns
We print everything to order so delivery times may vary but all unframed prints are despatched within 2-4 days via courier or recorded mail.
Due to the coronovirus pandemic and Brexit situation, current shipping times may be longer, particularly for destinations outside the UK.
Delivery to the UK is £5 for an unframed print of any size.
We will happily replace your order if everything isn’t 100% perfect.
