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Where did David H. Freedman get the idea that people without servants didn't worry about tidiness before the 1950s ( 19 January, p 22 )? This seems to be a case of a judgement made by looking in the wrong direction. Tidiness is mentioned in cookbooks from the 17th century. It is there in condemnation …

Could those who don't have this DNA be given it through some type of gene editing? Laurel Kornfeld looks for weight-loss hope in the finding of pieces of DNA associated with lower body weight ( 2 February, p 20 )

Breathless anticipation of a cashless society seems repeatedly justified on the basis both of convenience and its potential to undermine informal and criminal economies ( 12 January, p 22 ). But serious issues are overlooked. After natural disasters that take out electronic communications, such as solar storms and hurricanes, cash has a vital role to …

In late 2017, I decided to give a talk on fire to a science discussion group in the University of the Third Age. The occurrence of a supernova when savannah appeared ( 14 October 2017, p 7 ), black kites taking burning twigs to start new fires ( 13 January 2018, p 4 ) and …

I have been collecting lunar meteor impact recordings since November 1999, during the Leonids meteor storm. I believe I was the first to do so. I now work with the International Occultation Timing Association , a volunteer research organisation. You say that the observation of a lunar impact on 21 January was the first during …

Kelly Oakes suggests that a space elevator needs to be tethered at the equator to avoid hurricanes. ( 12 January, p 42 ). Regardless of weather, it must be terminated at the equator since its centre of mass must be in geosynchronous orbit. All such orbits are directly over the equator as defined by the …

Have the proponents of the space elevator done a risk assessment for a manufacturing error that results in a cable of length similar to the c ircumference of Earth coming whirling down?

• We printed photographs of the Extreme Light Infrastructure laser installation near Prague in the Czech Republic ( 26 January, p 40 ).

MacKenzie leaves to the end of her report the observation that ideology has frowned on governments messing with markets. Recent history has thrown up numerous examples of the private suppliers of essential services needing to appeal to public funds to bail them out of self-inflicted crises. An enterprise supposedly founded on the double principle of …

Before the antibiotic crisis , the Soviet Union put a lot of effort into using phage viruses that attack bacteria to treat diseases. Though under-reported in the West, this has continued, especially in Georgia, where the George Eliava Institute is a key centre. The editor writes: • This old idea is coming back. In 2015, …