Price 7s. Gd. Dr. Grifliths has takcn a line in this little volume which can be commended to other scientific writcrs who attenipt to deal with a large subject in a sniall spacc. Hc has written this trcatisc in such a way that it will form a uscful coniiccting link bctwccn tcxtbooks on heat on the onc hand ancl tcstboolrs on advanced pyromctry on the othcr. I-Ic has also avoided a common pitfall in works of this type by omitting t o describe pyrometers in dctail, nssuming that rcndcrs liavc aeccss t o manufacturers' catalogues. For thcsc rcasons alone thc work is t o be commended.
The subjccts dealt with arc expansion thcrmomctcrs including thc mcrcury-in-glass thcrmomctcr, salt and moltcn mctnl baths, nicrcury thcrmomcters for mcasuring surface tcmpcraturcs, transmitting and rccording thcrmometcrs and rapour prcssurc thcrmomctcrs. Anothcr chaptcr is dcvotccl to thcrmoelectric pyromcters, and in this chaptcr thc author sets out the principlcs of operation of the thormoclcctric instrumcnt in such a way that it can be easily understood by thc student, whilst providing intcrcsting and instructive reading for the most slrillcd uscr of pyromctcrs.