Your article (A brief history of sleep, 9 February) implies that Thomas Edison was the inventor of the incandescent electric lightbulb. While both he and Sir Joseph Wilson Swan were working to produce a suitable filament for a lightbulb, it was Swan – born in Sunderland – who demonstrated a working incandescent lightbulb using a carbon filament on 3 February 1879 at a meeting of the Literary and Philosophical Society of Newcastle upon Tyne, several months ahead of Edison. Swan is my great-grandfather.

Iona Devito

Haverfordwest, Pembrokeshire

• The Cockleshell Heroes did not destroy Grand Admiral Doenitz’s U-boat pens at Bordeaux in 1942 (Letters, 11 February). The concrete pens are still standing, undamaged even by RAF Lancasters. The men in the five kayaks of Operation Frankton were actually attempting to plant limpet mines on ships.

Andrew Rosthorn

Tockholes, Lancashire

• In your player ratings for England v France in the Six Nations (11 February), England right wing Chris Ashton gets 7/10 and his counterpart Damien Penaud 4/10. Yet your “team of the weekend” has Penaud at right wing rather than Ashton?

Mike Pender

Cardiff

• South Yorkshire is beyond the mountain hare’s natural southern range (Letters, 8 February). They were introduced into the Dark Peaks by the local landed gentry in the late 19th century for sport.

John Mosley

Leeds

• A “97-page magazine promoting Saudi Arabia” (Bezos v Enquirer, 9 February)? Something odd going on in the production process?

Simon Gray

Sheffield

• Join the debate – email guardian.letters@theguardian.com

• Read more Guardian letters – click here to visit gu.com/letters

• Do you have a photo you’d like to share with Guardian readers? Click here to upload it and we’ll publish the best submissions in the letters spread of our print edition